High-altitude Archaeolgy - August 2017

February 16 2017

Our August 2017 expedition plans to conduct an expanded archaeological survey, including a series of dives at extreme elevation, to investigate, map, and document pre-Incan/Incan ruins and artifacts in and around Laguna Sibinacocha located at 16,000 ft in the Peruvian Andes. Our expedition will utilize an OpenROV remotely operated vehicle (ROV) to document ruins and artifacts that we have already discovered in the lake, and to investigate and document new underwater sites, including those too deep for diving at such extreme altitudes. The ROV will also help target new dive sites, conserving the limited diving gas we’ll have at this remote location. An unmanned aerial vehicle (UAV) will be used to facilitate pedestrian surveys and to map the terrestrial findings and the surrounding landscape features.

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February 16 2017

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Name: Preston Sowell
E-Mail: sibinacocha@gmail.com
Account ID: 69101699


Mission Underway

One of our primary goals for this expedition was to retrieve offering pots that we discovered on the lakebed in 2012. Sibinacocha’s water level has been dropping in the last few years due to climate change and more recently, from lake water being piped to downstream villages. Subsequently, many of the ruin structures and the pots surrounding them are in shallower water, which allows more light penetration and therefore, more algae and aquatic plant growth. Features that were easily recognizable when I discovered them in 2011 are now completely covered with aquatic vegetation. This not only makes the structures and their surrounding offerings difficult to study, the vegetation growing on the pots also damages their surface. In 2015 our underwater archaeologists realized that the submerged cultural features were being covered and so they stabilized the one pot that we could still locate at that time. The pot was surrounded by sandbags to prevent algae growth on its surface and a buoy was placed next to it to ensure that it could be relocated. It’s also conceivable that the structures and pots could be out of the water in the very near future, which will make them more vulnerable to damage and looting. Therefore, the Peruvian Ministry of Culture granted the Peruvian Center for Maritime and Underwater Archaeology (CPAMS) team an emergency action permit to recover the pots that we could still locate.


Underwater archaeology is a relatively new discipline and that is especially true in Peru. The CPAMS underwater archaeology team is the first of its kind in Peru and we were all quite honored to be included in their effort. In fact, I’m told that this underwater artifact recovery was also a first in Peru, which is shocking considering the country’s rich cultural history. The CPAMS archaeologists believe that there must be more submerged sites like this in the Peruvian highlands, they just haven’t been discovered yet (we hope to change that soon!)…

Once the gases in our bodies safely equilibrated to the altitude, our dive team made a reconnaissance dive to inspect the state of the stabilized pot and to conduct systematic searches for the other pots. Dense vegetation thwarted our efforts to relocate the missing pots so we focused on recovering the stabilized pot. In recent years strong winds and storms have become more frequent in August, and that pattern was looking the same for this expedition. Concerned that bad weather might prevent us from safely recovering the pot, we chose to recover it with our first good weather window.

The day that I had waited years for had finally arrived. On August 20 the dive team entered the water to retrieve the pot. Under the supervision of CPAMS, we rehearsed the recovery effort on land to help ensure that the plan was executed smoothly. Every team member was assigned a specific task — both above and below the water. We were supervised by CPAMS archaeologist, Martin Polo, and artifact conservation specialist, Alexandra Sponza.

As I carefully removed the sandbags surrounding it, I was relieved to find the pot was intact and just as we’d left it two years before. We photographically documented its condition and then enacted the plan that we’d rehearsed. One diver removed the vegetation and sediment around the pot until we could tell if the bottom was intact and we were sure that it could be safely removed according to the plan. A sturdy, plastic crate was rigged with strong, kevlar cord and placed next to the pot. On cue, each diver executed their task until we passed the crate to waiting team members on the shoreline (check out the attached video. Password: Sibina). The pot was quickly transported to one of our expedition tents and Alexandra took over.

At that altitude, temperatures quickly drop to below freezing after sundown and we had a very old artifact filled with water. If that water were allowed to freeze, the pot could shatter. Alexandra set up a makeshift lab in the tent and a stove was lit inside to stave off the cold. She immediately siphoned off the water in the pot until only a thick layer of loose sediment remained. As the layers were removed we sat tense with anticipation as to what might be at the bottom of the pot. Suddenly she cracked a smile and said, “there’s something here…”

We all wondered what, if any, offering would be found inside, but one thing was in the back of everyone’s mind… gold. Golden figurines wouldn’t be too surprising for such a location and the precious metal is certainly the stuff of adventurous dreams. After a few more layers were removed, Alexandra knew that it was something hard and not seeds, coca leaves, or the remnants of cloth, which wouldn’t be too surprising either. She cleared enough of the sediment away from the objects to reveal their shape and photograph their configurations. Then, finally, she reached in and removed one of the objects. I could tell by her expression, it wasn’t gold. The weight of gold is unmistakable.

She placed the mud-covered objects on a plastic tray, just as they were positioned in the pot. They were clearly made of stone or some mineral. After a moment she sheepishly said, “what does that look like to you…?” Laughter erupted. The three stones were perfectly placed so that they looked like… well, look at the attached photo. They may have been meant as a fertility offering, and that wouldn’t be too surprising considering the potential significance of where we were. Regardless of what the stones were meant to represent, finding stones in such an offering was a first for all of the Peruvian archaeologists that we work with — just another ‘first’ for Sibinacocha. Alexandra still had more work to do to ensure that the pot was stabilized and conserved for future study, so the next day, we had a truck meet her back at the end of the road and she returned to Cusco to work in the lab that we’d set up there.

All of the sediment from the pot will be analyzed by Neal Michelutti, a paleolimnologist from Queen’s University. Since the pot acted as a catchment basin for sediment as soon as it was submerged, its makeup could teach us more about the historical environmental conditions in the lake, as well as the timeline for when the pot was submerged. As you can see from the attached photo, the algae had indeed pitted the surface of the pot and a section of the lip was broken out. Since we couldn’t find the missing piece in or around the pot, it’s possible that it was broken prior to being placed at the site. I took a stab at generating a 3D model of the pot using a series of orthophotos. The bottom wasn’t redendered in the model because I wasn’t able to photograph the bottom at the time. You can check it out the model at this link: https://sketchfab.com/models/a6d60614bfde4fef84ea4f8932ee7011 Password: Apacheta

We haven’t identified the origin of the stones inside the pot yet, but they don’t appear to be from rock that is native to the area surrounding Sibinacocha. Understanding where the stones came from will reveal something about the people who made these offerings. Initial analysis of the pot, based on its construction and shape, supports the archaeologist’s initial hypothesis that it was constructed in the mid-1400s. In the future, I hope to bring a technology that will see through the vegetation and sediment to locate the missing pots and recover them, and perhaps even map out the submerged structures without having to excavate the site.

But we still had work to do at Sibinacocha on this expedition, and two days later we broke camp and hiked around the lake to survey the area around the base of the rocky peak of Yayamari and hopefully, to search for sites on its 18,500-foot summit. I’ll report what we found there in the next post.

Password for the attached video: Sibina

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Preparation Stage

Hello all!


Firstly, the expedition was a great success and I have tons to share. I'm sorry for the delay in posting, but life is just starting to get back to normal. Hurricane Harvey that devastated Houston also decided to hit that city when my flight was scheduled to route through there, so... I had quite an epic getting home. Since then I have been unpacking gear and processing data.

I'll breakup up our field posts to reflect the basic activities around the expedition:

Well, my question about whether snow had hit the mountains was answered almost as soon as we left the main road and headed into Pitumarca. The mountains were white. Now the only question remaining was how deep the snow was and could we make it over Jahuaycate pass...?

Just above Pitumarca we stopped to view the remnants of an Inca road that follows our route into the mountains (or do we follow its route...?). Many of the Inca roads were paved with stone and very well constructed, so large sections of them are still used by inhabitants today. In the first photo you can see the stone stairway and some of the paving still intact on the trail.

Fortunately, most of the snow had fallen in the northern portion of the range and after many hours of driving, we safely reached the drop off point where our arrieros (horsemen) and 27 horses were waiting for us. They had walked for over a day from their village in Tinqui, which is on the north side of the Cordillera Vilcanota range. That required them to bring the horses over a higher, sustained pass called Campa pass. Unfortunately, one of our arrieros, René, did not bring sunglasses and was nearly snowblind by the time he arrived. I have worked with René for years and he is as strong as they come in the mountains, but he had to spend the next 24 hours in the tent and in extreme pain. You know the conditions are bad when one of these incredibly strong mountain men is taken out...

Walking over the ridge and seeing Sibinacocha again is always magic for me, and of course it's always a privilege to introduce the place to others. Four of our team members were new to the site and I was disappointed that the storm might destroy their first view. Fortunately, as our expedition dropped over the ridge into the lake's basin, the clouds lifted enough for us to feel the sun before we reached our first base camp just before dark (see photos).

After a cold night, woke the next morning to clear skies and began slowly unpacking and preparing our equipment. The first day at 16,000ft (4900m) is though, you typically have a light headache, you're out of breath, and it seems that everything requires monumental effort. So I was doubly impressed when Neal Michelutti and Chris Grooms with the Paleoecological Environmental Assessment and Research Lab (PEARL) from Ottawa inflated their boat and paddled out into the lake to begin immediately collecting sediment cores. Their goal was to collect preliminary data to guide a larger sediment coring expedition that we have planned for August 2018 (stay tuned...). The project will tell us quite a bit more about the local climate, what changes the lake has undergone (including lake level fluctuations that submerged the structures and artifacts that we were there to investigate), and will hopefully provide indications for when humans were using the area.

After unpacking I took the UAV up to shoot some test images and immediately crashed it when the program I was using froze. Lesson learned. My heart sank when I thought that I had ruined our opportunity to collect the aerial images and data that I planned to gather. Fortunately it happened just as I was landing and everything seemed to be working fine — with the exception of a broken propeller and bruised ego. Next we went to examine the dive site and to orient the new dive team members to the area. It would be another day before we could safely begin diving as the gases in our bodies needed to equilibrate to the new, thin atmosphere that we were in.

As were were walking to the dive site, I immediately found another arrowhead (see photos) and more looking revealed Incan pottery sherds, all of which our archaeologist, Martin Polo, quickly began documenting. We were off to a good start!

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PS. I don't know why that horse photo keeps posting upside down. I've tried to repost it a couple times. Just tilt your head...

Tried again and the horse photo just kept posting upside down. I uploaded some video of the horses instead!

Wow! Glad to hear the drone wasn't broken. And can't wait to hear what else you found. Great update.

Hello everyone! Sorry for the silence, there's been a lot going on from our end. We are in the process of loading the five 4x4 trucks that will transport us into the mountains to a small village at the end of the road. There, our team of arrieros (horse handlers) and 27 horses will be loaded with our gear and we'll begin the trek to our first Sibinacocha base camp. We've had to overcome some enormous logistical challenges this year so I haven't had time to post.


So... I only have time for the Cliff notes/bullet list version with a dump of photos, but I wanted to update everyone.

  • We nearly had to cancel the archaeological portion of our expedition until some generous donors came through at the last minute. Thank you all!!!! We will have archaeologists and an artifact conservation specialist with us to direct the recovery of threatened artifacts on the lakebed. We also received an emergency action permit from the Peruvian Ministry of Culture to authorize the work. More on this later.

  • The Innovation Center at St. Vrain Schools helped train me (thank you Lindsey!) on our new ROV and they helped troubleshoot some problems we had, which we unfortunately couldn't resolve. Fortunately, one of their units was free and they loaned it to the expedition so I do have an ROV with me!

  • I had to pack all of the gear you see laid out into 5 bags, but it barely fit and they all made it to Cusco, Peru (whew!).

  • The scuba tanks that were shipped to our team from Puno, Peru all arrived in Cusco completely empty - not much good for diving... But, friends in high places shipped a scuba compressor from the Peruvian Navy up from Lima and we filled our tanks in a field from above the ruins of Sacsayhuaman. That's a first...

  • It rained all night here in Cusco so I'm a little worried about snow in the mountains. I'll have the answer to that in about 6 hours...

All for now. Please wish us luck everyone!

Preston and the 2017 Sibinacocha Expedition team.

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Wow that's a lot of gear! Best of luck Preston and team. Looking forward to seeing what you find!

Any updates from the field??

One of the targets for exploration on our next expedition is a large spring formed by a sinkhole that is located about 600ft/200m above the lake (at 16,600ft/5092m) and at a potentially important location. It's about 30ft/10m deep and such locations were (and are) often considered sacred sites in the Andean cultures. Often called "ojos" or 'eyes', they sometimes received offerings, which were thrown into them. In the photo you see below, the nearly 20,000ft (6100m) mountain of Jatunriti can be seen in the background. The water that flows from its rapidly-receding glacier feeds the lake and, eventually, the Amazon river itself.


Since our limited diving gas is precious up there, and our dive gear has to move around on horses, the ROV will be critical for this site. We'll be able to explore the spring to determine if anything might be down there and therefore, if we should even attempt to dive at the site. Diving at these altitudes is serious business.

One concern I have are the aquatic plants growing around the edges and walls of the spring. Does anyone have experience with operating an OpenROV around aquatic vegetation? How much of a concern is prop-fouling? If the the propellers do foul, are they easily cleared without damaging the motors?

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Great post! Prop-fouling is definitely something to be on the watch for. Before each dive make sure to check to make sure the props are secure on the motor shafts (would hate to have you lose a prop there). If you start getting some uneven thrust when moving around then it would probably be good to check the motors. I think your best bet will be to do a trial dive for 5-10 minutes and then pull the ROV out and see if there is going to be any issues. To clear the motors you can unscrew the prop from the motor and then clear debris and then screw the prop back on (just make sure to tighten it all the way).

Thanks for the advice Brian. I'll do some testing in local ponds to try and test those limits and make sure that we have a 'pre-flight' checklist that is fulfilled before we drop our precious ROV into the water!

Well, it looks like our ROV learning curve has become considerably less steep. I toured the St. Vrain Valley Schools Innovation Center here in Colorado this week and I am incredibly impressed with what these kids are doing! I plan to recruit the team for our project.


Working with a team from the Denver Zoo, they actually built an OpenROV for scientists studying the Lake Titicaca Water Frog (Telmatobius culeus) in Bolivia. Some of the team members have Spanish language skills so they are communicating directly with the Bolivian scientists. They're also designing their own ROV for a specific need that the city has.

One team is also working on a remote-controlled water craft to collect bathymetry data for Colorado reservoirs to help with water management. We still need good bathymetry for our lake...

Another team is focused on adding instrumentation to an unmanned aerial vehicle (UAV) for the University Corporation for Atmospheric Research (UCAR).

Once we get our new ROV, I'm hoping lean on their experience and to work with this group to help us outfit it for our needs and to do some testing.

Thanks for Axel, Craig and the team for inviting me!

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Hi Preston,


We're glad you were able to come and we're glad to be able to assist you with your project!

-Aidan Sesnic and the rest of the Aquatic Robotics Team

Thanks Aidan! I'm looking forward to your team's help when the new ROV comes.

Although protecting Peru’s cultural heritage is the primary objective of the archaeological research, by documenting the cultural features in the watershed, our hope is to protect the incredible ecosystem that exists there, along with the mature climate and ecological research projects that have been ongoing since 2000. Nearly the entire Vilcanota range has been proposed as a conservation area due to its biological diversity and the fact that it is the most important reservoir of fresh water in southern Peru. Our team with the Sibinacocha Watershed Project is working with a local conservation group called the Association for the Conservation and Study of Andean Mountains – Amazonia (ACEMAA) to promote these conservation efforts.


Surrounded by 6,000m/20,000ft high glaciated peaks and lying entirely above 16,000 ft, the Sibinacocha watershed is an extreme environment by any standard, yet it contains stunning natural beauty and a remarkable array of wildlife. Herds of vicuña and taruka deer (a Vulnerable species) roam the local mountains, studies have documented 54 species of birds in the area — many at their world record altitudes — and the highest frog populations in the world live on a pass above the lake. Puma and Pampas cats (a Near-Threatened species) stalk the local hills, and the Endangered, Andean mountain cat, one of the world’s most rare and elusive felines, has recently been documented there. Surprisingly, a species of Liolaemus lizard even lives these altitudes. In fact, as climate change and rapid deglaciation occurs, the watershed serves as a “living laboratory” for multidisciplinary research investigations on climate change and alpine ecology. Still, previous studies have only scratched the surface and there is so much more to discover.

This vast, deep lake is full of life, yet it has never received a biological survey. Introduced trout are growing to enormous size feeding on the lake’s native fauna, which have evolved without the presence of such a predator.

Additional urgency to protect the watershed was added in 2006 when environmental scientist Preston Sowell glimpsed what was a different and larger species of the aquatic frog genus, Telmatobius. This frog is potentially a new species, unique to Sibinacocha and unknown to science; however, it also looked remarkably similar to the Critically Endangered, Lake Titicaca Water Frog (Telmatobius Culeus), which was famously documented in the depths of Titicaca by Jacques Cousteau when he took a submersible into the lake in 1973. With the ROV we also plan to search for our frog at depths that the divers can’t safely reach.

Whether it is indeed a new species or part of an introduced population of the Titicaca frog (they are smuggled throughout the region), scientific documentation of the amphibian would be important. With this in mind, Sowell searched for years to find the frog again. Using a different approach in 2011, he donned a wetsuit, mask, and snorkel, and entered the icy waters of Sibinacocha to look in deeper areas. Although he didn’t locate the frog, what Sowell found instead was astonishing. Far from shore, rock structures and other artifacts lay well below the surface.

Sowell’s discovery provides the extraordinary opportunity to document, study, and preserve a previously unknown, and significant pre-Hispanic cultural site, and in doing so, to hopefully provide the vehicle for protecting one of the world’s natural treasures.

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Here's an example of what we can create using UAV-generated orthophotos. This is a digital elevation model (DEM) of one of the archaeological sites that we've already found. It was done by our UAV wizard, Larkin Carey of Falkor Aerials using a DJI Phantom and DroneDeploy's software. We're hoping to produce DEM's for every one of the structures we find so that our archaeological team can more easily study them when we're out of the field. This tool also saves valuable time when we are working in such a large area and at elevations that make it difficult to cover ground quickly. Larkin reports that the altitude does make flying a bit more difficult and it really chews through batteries!


Also included is a still image from the same scene for comparison.

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Interesting. Are you using photogrammetry for the 3D models?

That's correct David. We program a flight path to collect sufficient photos (including enough oblique photos) so that an accurate 3D model can be generated using photogrammetry. The DEMs can then be collected from the same dataset. I'm finding that details jump out in the DEMs that are not as obvious in the still images or 3D models (and visa versa). If I can edit the post, I'll include a still image for comparison. Now, I'm looking into applying a similar technique underwater using an ROV, which I understand is a bit trickier.

Expedition Background

Lying at 5000m/16,000ft in the Cordillera Vilcanota range of southern Peru, Laguna Sibinacocha is the largest (2.4 x 18km/1.5x11mi) high-alpine lake in South America. In 2011, expedition leader Preston Sowell discovered submerged ruins in the lake and the finding corroborates local legends that tell of structures submerged there. A dam was constructed at the lake’s outlet in 1992, but the ruins are located below the maximum depth that the dam raised the water level, indicating that the ruin site’s immersion occurred in an earlier time period. Regional paleoclimate studies indicate that prolonged dry periods have caused significant fluctuations in regional lake levels. Notably, one of these droughts occurred between A.D. 1160 and 1500, which is when the structures were likely built on the lake’s historical shoreline.


The highland people viewed mountain lakes as sacred features in the landscape and ceremonial sites were often placed in proximity to significant lakes. It is also intriguing to note that archeologists consider the highland region around Sibinacocha to be a “blank spot on the map” relative to Andean archaeology.

In 2015 and 2016, Sowell mounted two National Geographic-funded archaeological expeditions to the site with a team of Peruvian archaeologists. Those expeditions revealed that one of the submerged structures is a 100m/300ft long structure depicting a snake and made entirely of golden-colored stone, which indicates sacred architecture. Zigzag lines representing a serpent appear repetitively in the region between A.D. 900 and 1532. What appear to be intact offering pots were also discovered on the surrounding lake bed. Ceramic experts in Peru dated one of the pots to the Late Intermediate Period (A.D. 1000-1470), which correlates to the dry period from A.D. 1160-1500.

On the 2016 expedition we discovered a complex of five to six structures in the area. Our archaeologists believe that the complex is the most significant find made at Sibinacocha to date. Ceramic fragments have been collected from the various sites that date from the Middle Horizon (A.D. 100-1000), Inca (A.D. 1470-1532), Colonial (A.D. 1532-1791), and contemporaneous periods. We’ve also collected numerous lithics, including arrowheads from the Archaic period (>1500 B.C.). The relatively high artifact densities were surprising for such a high and remote site, and the archaeological findings, coupled with an evaluation of sacred landscape features, indicate that Sibinacocha likely held ceremonial significance to pre-Hispanic populations.

As with the high altitude mountaintop, Incan, ceremonial sites, the submerged site presents an extraordinary opportunity to study a sacred, pre-Incan/Incan structure with its offerings intact and as they were originally placed. The discovery of such a site is a novel find, even in Peru. Unfortunately, the lake's rapidly dropping water level and its exceptionally clear waters are making the structures and artifacts more visible and more accessible from shore, which could facilitate looting.

In fact, the lake's entire watershed is currently under threat. As trekkers move through the area with increasing frequency (overflow from popular, nearby treks such as the Inca Trail), the historical structures and artifacts around the lakeshore remain unprotected. A mining concession has been granted on the pass above the north end of the lake, near its primarily water source. Prospecting is already being conducted and miners are frequenting the area. Laboratory analysis of the ore identifies high gold content, which means that the mining is likely to intensify. Alarmingly, the ore was also high in sulfur-bearing minerals (pyrite), which cause an irreversible reaction that creates acid rock drainage when exposed to air and water. This could irreversibly and catastrophically affect the cultural material and the riverine and lake ecology for many years to come.

EXPEDITION OBJECTIVES: The significance of the submerged structures and surrounding offerings lies in their extraordinary state of preservation and lack of physical disturbance. Rapidly changing environmental conditions in the Sibinacocha watershed, coupled with new anthropogenic threats, mean that the site is becoming vulnerable to damage and looting. Therefore, the goal of our 2017 expedition is to conduct a rapid survey of the area to define the extent, function(s), characteristics, construction material, and the amount and types of cultural material in order to facilitate a plan for site stabilization, protection, excavation, and the recovery of cultural material.

Due to the cold water, altitude, and remote location (limited scuba tanks can be carried in on horses), our team will use an OpenROV remotely operated vehicle (ROV) to document ruins and artifacts that we have already discovered in the lake, and to investigate and document new underwater sites, including those too deep for diving at such extreme altitudes. The ROV will also help target and prioritize new dive sites, maximizing the limited diving gas and underwater time that we’ll have at this remote location.

We will utilize a differential global positioning system (GPS) coupled with an unmanned aerial vehicle (UAV) copter with a high definition (HD) camera to capture drone-generated orthophotos, which will allow us to rapidly survey the cultural sites and their surrounding landscape features. This will allow us to generate maps and a 3D model of each location, which will help us better understand if/how the sites may be related to each other and to significant local and regional landscape features (i.e., their integration into the landscape). Under recent Peruvian law, landscapes designated as “Cultural Landscapes” (those modified and utilized for important cultural purposes), are afforded protection. Additionally, cosmological alignments were important to pre-Hispanic, Andean cultures and the 3D model will allow us to evaluate potential cosmological alignments between the structures and landscape features. We have already recognized important alignments at several of the sites.

Following the expedition, we will produce a written report for submittal to the Peruvian Ministry of Culture (MOC) to promote official cultural site recognition and associated protections.

This project is being conducted in conjunction with the Peruvian Center for Maritime and Underwater Archaeology/El Centro Peruano de Arqueología Marítima y Subacuática (CPAMS) and our expedition will mobilize in August 2017.

For more about the ecological and climate research being conducted in the area, please check out our non-profit's website: www.sibinacocha.org.

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Hello all! I'd love to hear your thoughts on creating 3D model using OpenROV products.

This is such a fascinating expedition. I'm really excited to learn more!

Thank you @margretsinsky! We have a lot to do and a ton to learn!

Insane diving! Cool project.

Thanks @Octopus Foundation! You guys are doing some great work as well!