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EXPLORING AND DOCUMENTING SA CONCA ‘E LOCOLI CAVE

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Text by Andrea Marassich. Photos courtesy of Phreatic. Header image: An inflatable (aka The love boat) is used to facilitate transportation of diving gear through the lakes.

Locoli cave is an amazing and challenging spring in the wilderness of Montalbo, Sardinia. It took me three years to set up the project, but it was all worth it. After all, David Rhea taught me that, “Slow is smooth, smooth is fast.”

I’m Andrea Marassich. I began exploring underwater caves in 2003, and I have taken part in cave exploration missions all around the world. In 2010, I fell in love with the powerful, majestic cave systems of Northern Sardinia, Italy. As a result, in 2014, I founded a nonprofit association, Phreatic, which collaborates with scientists and researchers in geology, paleontology, and earth sciences to study and document these unique environments. 

In 2019, I presented at Icnussa, the international speleology meeting in Sardinia, and spoke about Phreatic projects. During the event, a local caving club offered to carry diving gear to the first sump of a cave I had never heard of: Sa Conca ‘e Locoli. I dove with fellow GUE instructor Stefano Gualtieri, and  it was love at first sight. During the dive, I realized that I wanted to get back for more survey and exploration.

The Environment

“Locoli” is a temporary spring (active after rainfall and during certain seasons) located into Montalbo limestone massif, and is included in the UNESCO MaB (Man and the Biosphere) reserve of Tepilora, Rio Posada e Montalbo. 

Unesco Mab Tepilora Park: Karst, wetlands and coastline.

This Sardinian version of the Dolomites Alps, with its white rocks, looks out onto 25 km/16 miles of coastline. The silver ridge of Montalbo features evocative itineraries: historic trails for coal merchants and shepherds, archaeological sites, holm oak forests, and Mediterranean scrub (populated with mouflon, the golden eagle, and the red-billed chough). The peak presents doline valleys, chasms, underground rivers, as well as caves prehistorically inhabited by the Nuragic civilization. Archaeologists uncovered iron weapons in Bona Fraule, Gane ‘e Gortoe is rich in limestone concretions, Sa Conca ‘e Locoli  is eroded by the fierceness of the water, and Sa Prejone ‘e ‘Orcu is a cave-sanctuary.

Sa Conca’e Locoli

Locoli spring, which can submerge the whole valley during winter flooding, forms the entrance to the massive cave system hidden beneath Montalbo. The entrance cavern leads to a series of crystal-clear, freshwater lakes, and though the access is not technically complex, it requires the use of ropes through multiple changes of elevation, while the decorations and speleothems inside alternate with the smooth rocks levigated by water passage. 

Rope work and SRT is required to reach sump1. Hauling gear and physical effort is a serious part of the game.

After the lakes, the cave splits in two. The south passage leads to a shallow sump looping back downstream and connecting to a minor spring in the valley. The north passage goes through a series of changes in elevation, which require the use of ropes, and leads to a wide passage that provides access to the surface of Sump 1. 

This is the entrance gate to a series of huge flooded passages of breathtaking dimensions with obvious signs of a huge aquifer. The first sump is not particularly long or deep at 250 m/820 ft long with a maximum depth of 23 m/76 ft, but it leads to a very important second split. Here the subterranean river flows downstream toward the village of Siniscola and the Fruncu ‘e Oche spring, while on the upstream side it heads toward four other challenging sumps and dry areas. 

In the island of Sardinia, Sump 3 is the deepest, reaching 90 m/295 ft. 

The last exploration dive carried out in 2009 by Rick Stanton led to a collapse in Sump 5; consequently, the present survey only covers the first two sumps.  

The Project

In 2020, I organized the first scouting mission of the deeper sumps, together with Jan Medenwaldt. COVID-19 travel limitations presented difficulties in gathering a bigger team. 

In 2021, finally, we managed to organize a three-week campaign encompassing both survey and photogrammetry. The exploration of the system is particularly complex for a variety of reasons. First, the underwater portion is accessible after a relatively long dry passage, one in which cavers and cave divers must carry all their heavy gear. Subsequently, the series of sumps is difficult from a technical point of view, as the diving profiles involve serious exposures in Sump 3 and 5. 

After the dives were completed, the long clean up requires a couple days, but the smile don’t lie. Operations went smooth.

In order to complete the working goals connected with survey, mapping, photo/video, and research tasks, divers needed to extend their diving time and elected to stay inside the cave and set up a bivouac; entering the cave with dry tubes and bivouac gear without knowing where to establish the camp was risky. We found a new dry section between Sump 3 and 4, which proved to be ideal to bivouac and minimize the decompression risks connected with the profile. 

The main challenge is dealing with the geology of the cave, one that presents multiple elevation changes to move from one sump to the next. Sump 3 is the most demanding of the five underwater galleries, as the cave drops initially to 45 m/148 ft deep, then rises to 15 m/49 ft, drops to 90 m/295 ft, ascends again to 45 m/148 ft, and drops again to 65 m/213 ft before the final ascent. 

We deeply believe exploration without documentation is not getting the job done. Survey and documenting with media is a key component of our activities and we prioritize it over simply “reaching a distance”.

The exploration efforts are now divided in two areas: the newly discovered dry section between Sump 3 and Sump 4, featuring massive rooms and high chimneys that potentially connect with a fossil gallery above, and Sump 5, whose exploration stopped at a depth of 50 m/164 ft and needs  further investigation.

We are already working on new project sessions for summer 2022. 

Considering the importance of the karst system of Montalbo and its water reservoirs, the UNESCO MaB reserve decided to support our project, specifically in relation to our documentation and conservation efforts. We also received the sponsorship of the Italian Speleological Society and are now searching for more partners. 

The main objectives will be:

  • Completing the survey of the upstream section up to Sump 5. To perform this task, we will use the SUEX DRIVe and mapping devices combined with MNemo.
  • Creating a documentary featuring the most beautiful passages of the cave with the help of an expert photogrammeter and videographer.
  • Improving public awareness about caves and karst in partnership with the International Year of Karst and Cave initiative provided by the International Union of Speleology.


Citizen Science

Phreatic believes in the power of Citizen Science. All our projects and missions rely upon the crucial involvement of skilled, specially trained individuals. The Sa Conca ‘e Locoli cave project involves a number of local and foreign volunteers with various sets of competences. Many thanks to Speleo Club Nuorese for the support in the dry portions of the cave, and to all the Phreatic volunteers who joined us in 2021 including Jan Medenwaldt, Peter Brandt, Sven Bertelmann, Keith Kreitner, Laura Marroni, Elke Riedl, and Irene Homberger. 

Entrance of one of the multiple downstream passages; While one team was diving the upstream sumps and bivouacked in the further section, operations continued with oc team working in a different area.

Collaborations and Partnerships

Phreatic can count on a long-term partnership with SUEX, a world leader in high-performance underwater vehicles designed for long-range technical and professional diving.

The Locoli project operates under the supervision of the geologist Dr. Francesco Murgia, author of multiple scientific publications on the areas of Montalbo and Supramonte.

For more information see: Phreatic: Citizen Science and Groundwater Research. Email contact: info@phreatic.org

Cave

Plan The Shoot, Shoot The Plan

Gas planning is an essential part of tech diving but how does it apply if you’re planning to conduct a photoshoot in multiple specific locations in the overhead environment of a cave? Arguably one of the most artful cave photographers today, and a high-level tech diver, Fan Ping explains how he calculates gas requirements when making pretty pictures in the dark!

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By Fan Ping. Header image: Bedding Plane at Jug Hole by Fan Ping.

Plan the dive, dive the plan. That’s something I have been hearing since the beginning of my diving career but never really mastered until I started my cave diving training with Global Underwater Explorers (GUE). I was surprised by how powerful dive planning can be as a tool, down to a minute, a meter and a few bars. Of course, there is flexibility, but the whole point is you will be aware of what is going to happen next, and have control over the entire process of the dive.

Planning can also apply to underwater cave photoshoots and filming. As a fulltime underwater photographer and director of photography (DP), I plan my shoots in the caves all the time and teach it as a part of my Underwater Cave Photography Course. It definitely makes my job much safer and more efficient. There are two parts of the shoot plan: diving and photography. They work together and can sometimes be complicated, especially when shooting at more than one location. I usually start with the diving part. Knowing exactly where I am going for the photo, I can easily calculate how much time and gas I am going to use to get to the location, and then recalculate a third so I know how much time I have to shoot the photo.

Then I plan the photo part, usually based on a sketch with lighting indicated. Having a sketch of the photo can be very helpful, as it tells me how many lights I am going to need in total and where to put them, both on location as well as when traveling with them. I will also know how much time I am going to need to place and retrieve them, and that adds to the total bottom time too, so I can have a relatively accurate time for actually clicking the shutter.

Plan The Shoot on CCR

It’s the diving part again after the shoot—whether to a second location or to the exit—and in the end, I will have a deco time and total runtime, so I can make sure we are not locked in the park and have somewhere to go for dinner.

Red is in, blue is out, shoot location is in yellow. Map created by Jeff Hancock, partially shown for planning purpose only.

Let’s start with a more straightforward example with one location on rebreather. My buddy Derek Dunlop and I planned a photoshoot at the fissure on Sweet Surprise line in Ginnie Springs. We wanted to scooter to the jump at 670 m/2200 ft on mainline in 20 minutes, drop DPV and sidemount bailout, then swim for another 200 m/656 ft to the shoot location in 20 minutes. The depth of the location is about 28 m/92 ft, which is also the maximum depth of this dive, and the average depth is about 24 m/79 ft before 6 m/20 ft deco, so it was well within our bailout radius, somewhat conservative considering the flow in this cave. (I have LP50 or 7.8L doubles + 1x sidemount 11L, Derek has 2x LP85 or 12L OC bailout. Assume we both have 11L x 2 x 200bar = 4400L OC bailout gas, SCR = 20L/min, ATA = 4, so we have 4400/20/4 = 55min to get back to the cavern. Swim speed = 10m/min, DPV speed = 40m/min, and it will take no more than 40 min in a real situation.)

We plan to shoot until the batteries of the lights die, which will take 40-45 minutes, plus 10-15 minutes to place and retrieve the lights, so it’s a 1 hour shoot at the location. That gives us a 150 minute bottom time plus 25-30 minutes of deco at 6m/20 ft (O2 setpoint: 1.2 bar), 3 hour total runtime.

Derek at the fissure. Most walls are very dark as it’s less traveled.

I usually use the GUE EDGE, i.e., GUE’s predive checklist, for planning, as it is a very good base to start with, no matter if you were trained with GUE or not, and it is very difficult to miss important information with it:

Goals: Photo at fissure on Sweet Surprise line. 

Unified Team: Derek diver # 1 and model, Ping diver # 2 and photographer.

Equipment match: Derek has 1 light on tripod, Ping has camera and 4 lights.

Exposure: Max depth 28m, average depth 20m; 20 min on DPV to jump, 20 min swim to shoot location, turn at 100 min. Total runtime 180 min.

Decompression: 30 minutes deco.

Gas: Sufficient OC bailout gas for each diver, 5.7L AL tank filled with oxygen to 200 bar.

Environment: Normal flow.

Filming at Jug Hole back in 2019.

Plan the Shoot—Open Circuit Edition

Here is another example of a short but multiple location photo shoot at Jug Hole in Ichetucknee Springs State Park, Florida, with my buddy cave diving instructor Joseph Seda as the model.

We planned to take a photo at the Diamond Sands restriction first, then an HDR panorama photo in the bedding plane right after the reaper sign, and a cavern shot if not too late.

The Diamond Sands restriction is only 80 m/262 ft on the mainline, but the flow in this cave is strong, and the bedding plane at the beginning is very low, so my swim speed would be about 8m/s, and it will take me 10 minutes to get to the first shoot location from the cavern. 

Average depth for this part is about 15 m/49 ft, maximum depth is 22 m/72 ft at the restriction. I have a very standard 20L/min SCR, so with 2 sidemount LP85 steel tanks (12L) I am going to use roughly 30 bar in each tank (5 bar/5 min with 12L doubles) before I can start playing with the lights.

Map created and authorized by Adam Hughes.

My tanks are filled with 32% to 260 bar (welcome to cave country!), so theoretically I have 260-30-30×2=170 bar to use for the first shot, with the depth of 22 m/72 ft, it gives me about 35 minutes before I have to turn the dive. 

Lighting is relatively simple here, just 1 light from the model’s back and 2 on the camera, so it will take only a couple of minutes to set up. Diamond Sands restriction is famous for the rolling sands in the flow when a diver passes, and that’s what we want in the photo, obviously from the exit side, and that makes my job easier, as Joseph will be the one placing the light in the back and coming back out of the restriction to pose. So he is diver #1, going in with two lights on tripod (one as backup and for shot two).

Going back to the bedding plane for the second shot only takes about 5 minutes, and getting out of the cave from there will take no more than 5 minutes too, which is about 15 bars in each tank. So usable gas for the second shot is 260-30-170-15-15×2=15 bar.

Diamond Sands restriction. Enlarge to see the rolling sands.

At 15 m/49 ft it gives me only 5 minutes, and I am supposed to get out of the cave with at least 50 bar in each tank, so we will have to shorten the first shot in order to get the second shot, which is a lot more complicated with 6 lights in total to light up the whole scene.

In the end, we got a shoot plan like this with GUE EDGE:

Goals:  Photos at Diamond Sands restriction and in bedding plane.

Unified team: Joseph diver # 1 and model + light monkey for shot 1, Ping diver # 2 and photographer + light monkey for shot 2.

Equipment match: Joseph has 2 lights on tripod, Ping has camera and 4 lights.

Exposure: Max depth 22 m/22 ft, average depth 18 m/59 ft; 10 min to location one, 20 min for shot 1; 5 min to location two, 30 min for shot two, 5 min to cavern.

Total runtime: 70 min.

Decompression: Minimum deco.

Gas: 260 bar to start, 170 bar to finish shot 1, 80 bar to finish shot 2.

Environment: Strong flow, restriction and sandy bottom at location one, very low bedding plane at location two.

*This calculation is relatively conservative, we have twice the amount of gas we need to get out of the cave at any point.

Plan for Safety

The purpose of planning the photo shoot is to make sure we don’t put ourselves in danger while being too focused on the camera in underwater caves. Open water photography is a lot less stringent in terms of planning; however, overhead environments require more precise ideas for how much time it takes to do the job, especially on open circuit. Good planning also makes the shoot more efficient by reducing unnecessary communication and setting up the scene as a team, which eventually leads to a safer dive. There is not one single photo worth a diver’s life, but there are countless caves that are worth diving with a camera

“There is not one single photo worth a diver’s life, but there are countless caves that are worth diving with a camera.”

Dive Deeper

InDEPTH: Cameras Kill Cavers… Again by Natalie Gibb

Here are some of Ping’s other stories:

InDEPTH: Close Calls: I Ripped My Drysuit a Kilometer Back In The Cave by Fan Ping

InDEPTH: Underwater Galaxy by Fan Ping


Fan Ping is a photographer and filmmaker based in Atlanta, Georgia, USA, and is dedicated to showing the beauty of the underwater world to people through his lens. He is specialized in combining artistic elements with nature and complex lighting skills in overhead environments, and this artistic style has brought him international acclaim, including awards from many major underwater photo/video competitions. You can follow his work on Facebook and Instagram: Be Water Imaging.


Be Water Imaging’s Underwater Cave Photography Course is a modular course that includes unique lighting skills and advanced photography techniques in underwater caverns and caves, and shoot planning is a very important part of the course. For more details please check my Be Water Imaging website, and contact Ping at: info@bewaterimaging.com.

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