I think we all understand the problem with plastic. Many of the disposable plastic items we use in everyday life are made from a material that lasts forever. These items don’t break down, they break up, into smaller and smaller pieces.

Plastic is ending up in our oceans and our marine life. It’s finding its way into the food chain and the fish we like to eat. Much to my horror, I have discovered that plastic is finding its way into caves too.

I recently spent a couple of months cave diving in Mexico. The Yucatan Peninsula is a mecca for cave divers. Hundreds of kilometres of underwater caves connect hundreds of cenotes. The underground aquifer is amazing and I feel fortunate to have had this amazing experience.

The water in the caves is often crystal clear. People comment on my underwater photos “is there even water in there?” Swimming through the cave, you can imagine you’re swimming in a pristine environment. It may be an illusion though. Human activity on the land above the cave systems means that the water isn’t drinkable without treatment. Ear infections are common.

On the last day of my trip I went for one final cave dive. I drove to the spectacular Cenote Nohoch Nah Chich. Nohoch is a very popular cave diving site. It has shallow tunnels decorated with elaborate white formations. The clarity of the water is breathtaking. Most cave divers head upstream and I usually do too.

This time I decided to go downstream. The downstream cave has a different feel. The silty floor is darker from organic material washing into the cave. The cave is punctuated with air domes. White columns clash with the dark floor. It’s beautiful. It’s also contaminated with plastic.

Passing by an air dome, a flash of vibrant pink grabbed my attention. Playing my light across the water’s surface, I could see brightly coloured objects floating. They were caught up with crystalline calcite rafting and buoyant seed pods (both natural features). At first glance there were plastic bottle caps and those bottle security ties that you rip off a sealed water bottle before you guzzle it. There were brightly coloured objects I couldn’t immediately identify, except to say that it all looked like plastic.

I kept diving but I couldn’t get my mind off the rubbish. I wasn’t about to leave it in the cave. On the way out I signalled my team mate Cameron, who is also my spouse. I asked him to join me and help me grab what floating plastic we could from the air dome. He wasn’t particularly happy about it, which I could understand. What cave diver wants their last memory of a great trip to be of collecting garbage?

We collected as much plastic as we could stuff into our drysuit zipper pockets. This was a challenge; each time the zipper was opened buoyant fragments attempted an escape towards the cave ceiling. Cameron found a plastic bottle with a cap. He was able to wedge this full of other plastic fragments for easy transport out of the cave.

It was a miserable job. Not the collecting of the plastic. Simply seeing all this waste from human activity messing up a natural environment.

I wondered… where is all the plastic coming from? Cenote Nohoch Nah Chich is a popular tourist site. Snorkellers make up most of the traffic. The cenote has a generous cavern zone where you can snorkel into the overhang. Perhaps those swimmers have plastic items in their pockets: chapsticks, hand sanitiser, pens and chocolate wrappers.

I also collected twenty brightly-coloured plastic loops in the shape of springs. They looked like some kind of bangle. This fashion trend completely passed me by and they surely don’t belong in the cave.

What can we do about this insidious plastic invasion? We can choose to refuse plastic wherever possible. Refill your water bottle from a trusted source every day instead of buying bottled water. Plastic bottle caps (from water and sodas) were the most abundant item recovered from the cave.

We can all pick up litter even if it’s not our own. This is especially important around water such as the sea or freshwater sites like cenotes and streams. When it rains garbage is transported downhill to the water. It’s easier to keep water clean than clean it up.

We can also spread awareness. There’s a global movement challenging our current thinking around how we use plastic in our lives. Plastic Free July is about motivating people to refuse single-use plastic items and find a way to live without them. There are really easy places to start, such as bringing your own reusable bags to the supermarket for your groceries.

Finding plastic inside an underwater cave was disturbing. We need to take more care of our water. Next time you go for a swim, check your pockets for unsecured items. Please be careful how you dispose of plastic around Mexico’s stunning cenotes. We want them to stay that way. #choosetorefuse

Cenote Zapote must be the world’s weirdest dive site. From the surface this enticing orb loaded with crystal clear water and lush plants reveals nothing of the mind-blowing formations called Hell's Bells found within. If you assemble your scuba gear and slip below the surface down the hour glass to a depth of 28 metres, what you see will knock your fins off.

Little is known of the enigma that is Hell’s Bells. How were they formed? Why are they found here? Why is there no other dive site quite like this one? There's only one thing I know for sure... you've got to see it to believe it.

The underwater cavern of Cenote Zapote is much bigger than you might believe from the surface. The entrance shaft pinches in at 21 metres before ballooning out into a spectacular room that undercuts the rock. A thick layer of noxious hydrogen sulphide is found between 35 and 42 metres. Trees from the talus cone (the cone of debris and scree material that has fallen into the cenote) poke up through the cloud.

A lined ring route has been laid through the bell formations and takes you around the perimeter. The depth on the line varies from 28 to 33 metres. There is one T intersection with the stem of the T extending back into the centre of the circle and tied off to a tree.

If you are diving trimix and head below the hydrogen sulphide expect it to be completely dark below (cave training and technical training highly recommended). There is a line that circumnavigates the debris cone. Scientific studies are being performed below the hydrogen sulphide on the skeleton of a sloth. Please respect the investigation by staying well clear and not touching or disturbing anything with fingers or fins.

A small section of cave has been explored.

Cenote Zapote is located west of Puerto Morelos in Mexico's Yucatan Peninsula.
 
Get off the main Cancun-Tulum highway 307 at Puerto Morelos. Travel south on the lane next to the highway and turn right at the road headed inland signposted to Central Vallarta, Hol-Box and Ruta de los Cenotes. Travel 19 kilometres on this road then turn left into a gravel road (big sign post for Zapote Ecopark and Kin-Ha Natural Park).
 
Stay on the main wide gravel road for 6.3 kilometres. At one point you turn left. There are signs along the way for Cenote Zapote and Kin-Ha. At roughly 6.3 kilometres on the gravel road turn left at the big Cenote Zapote sign.

Entry fee for scuba divers:
$400 Mexican pesos per person (April 2017) - cash only.

Depth:
The Hell's Bells formations are found at around 28 metres or 90 feet. The line that circumnavigates the formations goes down to 33 metres or 110 feet. The hydrogen sulphide layer starts at about 35 metres or 115 feet.

Facilities:
Very nice bathrooms, open air showers, two platforms for leaping off into Cenote Zapote, small number of car parks next to site.
 
The park also contains Cenote Palmas and Cenote El Abuelo - ziplining, swimming, snorkelling, bicycling and tours available.

Warning:
This dive site is deep and takes you into the overhead environment (and away from direct access to the surface). Some kind of cavern training at a minimum would be sensible, along with a redundant gear configuration and gas planning. Consider 30/30 gas for this site.

People leap off the platform into the water. It's recommended that scuba divers take note of the direction of the far side of the cenote so that you can surface safely away from the platform at the end of your dive.

Map:
The Zero Gravity dive shop has a nice cross-section map of this underwater site on their wall. Drop into their dive centre to take a look. They also hire double tanks and do trimix fills. They are located off the roundabout at Puerto Aventuras.

Photography:
Canon 5D Mark II camera in Sealux housing with 14mm lens and Inon Z240 strobes fired by Triggerfish.

More Information:
Cenotes Zapote Ecopark website.
Cenotes Zapote on Twitter.
Cenotes Zapote on Facebook.
Cenotes Zapote on Instagram.

While many consider the deep ocean to be the last great unexplored frontier on planet Earth, cave divers are quietly travelling kilometres underwater and underground, and returning with extraordinary news. Here is evidence of animal tracks from the floors of a submerged cave system in the eastern Yucatan Peninsula in Mexico. Considering that these caves were inundated with water following the last glacial period, this could make the footprints thousands of years old.

When you cave dive there’s a real sense of exploration and that you’re diving where few have travelled before. Deep inside the beating heart of mother Earth, inside her watery system of veins, cave divers are pushing the boundaries of where we’ve been before and what we know about the mysterious underground.
 
Cave divers Sam Meacham and Alex Alvarez returned from a dive and reported that they had seen what they believed to be footprints in solidified mud on the cave floor; I was skeptical. There was a fair amount of jovial banter and good-natured ribbing between friends. I had to eat my words when Sam produced a GoPro from his pocket and played a video on the tiny screen. He seemed to have something and I was excited.

Neatly imprinted in mud as if they walked there only yesterday were 3 and 4-toed pawprints from a small animal. Suspended in water, breathing compressed gas from a scuba tank, you might imagine how startling this would be to a cave diver making a foray into the lightless tunnels. My heart nearly leapt out of my chest the first time I saw the prints.
 
To visit the cave at a time when it was dry enough to have a muddy floor on which to record animal footsteps would be to visit the cave not hundreds of years ago, but thousands. The Mexican caves of the Yucatan Peninsula were dry during the last ice age of the Pleistocene when global sea level was lower. When the glaciers melted they released their trapped water into the ocean and flooded the caves.

Animal tracks have now been recorded from several different locations within the Sac Actun cave system. I believe that the footprints come from an animal similar to a paca (Agouti paca / Cuniculus paca). The paca is a small terrestrial rodent under three feet long that is mainly nocturnal.
 
In the book Mammals of the Yucatan Peninsula (2009) the paca is described as having “four toes on each forepaw, and five on each hindpaw. Generally, its tracks show only three toes, with non-retractile claws.”1
 
From the number of tracks now recorded, I assume that there was considerable traffic by animals around the cave. While I don’t know what the animals were doing in there, I do know that these were not the only animals to make their way through the tunnels. Skeletal remains of gomphothere, sabertooth cats, giant ground sloths, bears, tapirs and other animals have been documented from inside the cave systems of the area. The most famous remains are those of Naia, a human skeleton found in the submerged collapse chamber of Hoyo Negro and dated to be between 12,000 and 13,000 years old.2

Now that I know that we are cave diving in the footsteps of ancient animals I hope that others can also be on the look out for more sites of interest. It would be great to get a scientist involved so that we can all learn more about the history of the caves and their importance to ancient animals of the Yucatan Peninsula. Perhaps we can harness the power of the citizen scientist and form a collaboration between scientists and cave divers, as has already proved to be so successful on the Hoyo Negro Project, the study of a submerged Paleo-Indian site.
 
Deep horizontal cave penetration may not be as sexy as deep ocean exploration. It doesn’t involve submersibles and complex space-age-like gadgetry, and there are few living creatures (monsters of the deep) with which to ignite the public imagination. But locked inside water-filled underground chambers are prehistoric clues to ancient civilisations and if cave divers can be alert to these signs and conscious not to disturb the evidence, we can bring these new discoveries into the light for all to see.

References

1. Biol. Carlos Alcerreca A., Biol. Rafael Robles de B., Biol. Luis Pereira Lara, Biol. Diana Antochew Alonzo, Dr. Fiona Reid. (2009) Mammals of the Yucatan Peninsula. Mexico: Editorial Dante S.A. de C.V., pp. 228-229.

2. James C. Chatters, Douglas J. Kennett, Yemane Asmerom, Brian M. Kemp, Victor Polyak, Alberto Nava Blank, Patricia A. Beddows, Eduard Reinhardt, Joaquin Arroyo-Cabrales, Deborah A. Bolnick, Ripan S. Malhi, Brendan J. Culleton, Pilar Luna Erreguerena, Dominique Rissolo, Shanti Morell-Hart, Thomas W. Stafford Jr. (2014) Late Pleistocene Human Skeleton and mtDNA Link Paleoamericans and Modern Native Americans. Science, 344(6185), pp. 750-754.

You might have noticed a change in the style of my cave diving photographs. In the past I have shot more photos of my diving models front/face on. Recently I've shot more of my model’s butt - their delightful rear end. This is likely to continue and I’d like to explain why.

With the aid of DPVs (diver propulsion vehicles, also known as scooters) I am now travelling further into caves than ever before. This is amazing because it’s taking me into cave passages I’ve never seen before. New cave = new discoveries. It also brings with it many photographic challenges.

Diving a greater distance into caves means reaching passages that few divers ever get to. In tunnels that have seen very little diver traffic it is quite common to experience a lot of percolation. When exhaled gas hits the ceiling, rock flour and fragments are dislodged and start raining down. This ruins the visibility of the crystal clear water and is a backscatter nightmare.

Percolation means that I have almost no time to fire off my shot before the conditions for photography deteriorate dramatically. Cave passage that sees a lot of diver traffic generally has a lot less percolation as the tunnel has been cleaned by loads of bubbles hitting the ceiling. Percolation needs to be avoided.

Swimming a longer distance into a cave also means that the time to take photos is limited. I can only breathe the gas from the tanks that I can carry. When I’m deep inside a cave the clock is ticking and the pressure to get off some shots before my dive team has to leave is high.

For these reasons I am now introducing more of the butt shot - shooting photos of my partner and model Cameron from behind. This allows me to take photographs on the move as we swim through the cave. Shooting while moving means I can keep ahead of the percolation and photograph through clearer water. I can also fire off more shots in the small amount of time I have before my gas runs out and I have to turn around and head for the exit.

Why shoot underwater caves with a diver model at all?

The greatest challenge of cave diving photography (all photography) is light. In caves I have no natural light to play with; I have to bring my own light sources with me. I shoot with a model in my cave photos for three reasons.

1. The diver provides a sense of scale for the cave. It allows the viewer to get a feel for how big, or perhaps small, the cave is. With no diver it’s very hard to comprehend how big the features in the photo are - most people are not immediately familiar with caves.
2. It tells my audience that my photograph was taken underwater. Sometimes I’m shooting through water that is so clear it’s not obvious in the final photo that this is a water-filled cave. I want to take my audience underwater with me - the cave diver sets the scene.
3. My model is a mobile source of light. My diving team carry strobes (flashes) which are fired remotely from my camera. By moving my model I can change how I light up the scene and create depth in my image. This is one of the best ways to shoot and be sensitive to the pristine nature of the cave environment. An alternative would be to place strobes around the cave, but it’s very difficult to place anything on a cave floor without leaving some kind of mark in the silt. An unmarked silt floor is one of the most beautiful things we can leave behind us when we depart the cave. Take only photos, leave only bubbles.
   

There's no question that people respond to photos of people. I am well aware that the front-on face shot is a crowd favourite. My cave diving partner Cameron has a nice bum, but his face is even nicer. :-)

This change in my shooting style reflects the adaptations I am making to try to capture photos of underwater caves that may not have been photographed much, if at all, before. New cave means new challenges and trialling new techniques to improve on my underwater photography.

So what do you think of this change? Your feedback is welcomed - leave a comment below.

2016 may be the year of the butt shot.