Diving at Cenote Santa Maria
Located just south of Tulum, off the 307 highway, CENOTE SANTA MARIA is on a private ranch. A few divers had been in there exploring, but the last was an old housemate of mine who thought I might be able to find some new cave. While the 2020 pandemic was in full swing, not being able to work or visit public cenotes meant we started to look at other options for diving. Being on private land, we were able to go there and dive when many other sites were close. And we were able to explore a whole bunch of new cave!
Divers swim through the The Big Room.
Exploration history
My former housemate Mariano had told me about this cenote towards the end of 2019. At the end of November we visited Rancho Santa María and he introduced me to Don Ramon, who showed me the cenote and invited me back to dive. It was a few months later, at the end of February, that I had time to dive the cenote. Mariano had warned me about a tricky entry and that the line was not easy to find… of course I took this to mean it just took a little hunting and off you go. I mean, there is only a small area where the cave opening can be right? I very quickly realised how wrong I was! Spool in hand I entered the water which was already quite murky due to algae. Where I assumed the entry was did not open up, and trying to enter a dead end past a mound of organic silt only caused zero visibility. No worries, I told myself, I’ll find it by feel, it has got to be here somewhere! After 45 minutes of zero visibility groping I gave up. Despite this set-back, another trip to Santa Maria with Mariano, this time with clear water and improved visibility, resulted in the cave line from open water being found. Line in hand I ducked under the ledge and popped into the first giant chamber. Now the diving could begin!
The first big chamber after the entrance.
According to Jim Coke at the Quintana Roo Speleological Survey the cave was historically reported as Cenote San Pedro. It was first explored in 2007 by Alex Anisimov and Victor Trostyanskiy. Bil Phillips and Tristan Bond Evans followed the Russian leads and explored three more smaller side passages in 2012. Later there were some further small passages added by unknown explorers, Mariano Schaller and Noe Caffesse. My first task was a systematic resurvey of the lines and mark potential leads to return to. See image of the map! With only 1600 feet of existing line this was easily done over two dives with just sidemount tanks. At the end of the second resurvey dive, I noticed that the cave seemed to open up at the bottom of the slope. Tying into the end of the existing line I descended down the slope, paused and looked to the side. Past a restriction the cave opened up. And the water was that electric blue characteristic of a salt water section!! Boom! Mega cool, going, cave tunnel!!
With the ProTec team I did a lot of diving here. Over many dives we extended the extent of the cave from 1,600 feet to more than 15,000 feet! But the exploration diving there is another story….
The back of the super decorated room.
Cave features
This is a cave that changes a lot! Initially the upstream cave is a series of giant rooms. Cave diving up the mainline, a t intersection allows divers to turn to the upstream or downstream section of the cave. The cave upstream has lots of fossilised corals and shells, and is characterised by some really unusual reddish and orange tones in the walls and floor. In the ‘big room’ before the line drops into the saltwater the cave is festooned with decorations. If you look closer, there are some amazing formations formed by splashing of the droplets of water when the cave was dry. Getting down to 18 meters / 60 feet you start to see traces of halocline, the interface between the fresh and salt waters. What has been really cool is to dive here a lot and see how the depth of the halocline changes with the seasons. When there has been lots of rain, there is more freshwater which pushes the salt water deep. Conversely, when there have been months without rain, the halocline is shallower. This also highlights the importance of fresh water as a resource, if overused it could lead to salt water shallower and shallower (as much of Tulum’s water comes from shallow bore wells, this could lead to salt or brackish water in your shower or kitchen sink).
Part of the saltwater section.
What I consider to be the middle section of the cave is a series of salt water tunnels that link the up and downstreams. This was the first new area of cave I explored and I still remember that feeling of excitement running the reel through a low, wide slot to pop into a beautifully decorated saltwater passage! The tunnel and big rooms are very decorated with reddish features and lots of white walls. There are a few offshoot tunnels that eventually terminate in breakdowns. Heading towards the downstream side there are numerous restrictions, before the tunnel becomes more of a bedding plane. Shallowing up through a low restriction, the cave opens back up, but looks completely different to the upstream.
The halocline on the way to the downstream.
The downstream cave is a very white cave, with very swiss cheese looking rocks and percolation, lots of percolation. Because of the flow, the aggressive halocline, or different chemistries in the water, the rock is a lot more eroded. The tunnels here look a lot more like the halocline tunnels of Cenote Ponderosa. As you continue to dive further into the cave, rooms open up that are highly tannic, or really decorated. It continues to surprise you the further in you go. While there are many jumps along the way, they are all fairly short and loop back onto the mainline.
DIVING THE CAVE — Santa Maria is a relatively small cave by Mexico’s standards. By doing two sidemount dives, you can quite comfortably dive upstream and a second downstream. The entrance, and many of the restrictions mean that the cave is sidemount only. A lot of great caves can be visited with a single stage tank also (although this does introduce the possibility of decompression obligations). The entrance is a bit awkward and so passing with double stages is not really possible (and it leaves zero visibility for the second diver). However, we did most of the exploration with our KISS Sidewinder Closed Circuit Rebreathers, and this is a fantastic cave for CCR diving!
Santa Maria is an interesting little cave which holds a special place in my heart as one of the few places we explored that is easily accessible for divers to visit. We spent a lot of time diving here, and I have a lot of good memories diving with friends here. The cave has some pretty peculiar features and changes a lot between the upstream and downstream sections. This is a good place for experienced sidemount cave divers to visit if they want to see something a bit more off the beaten track, without having to do any jungle hiking!
The big decorated room.
Photos by Alvaro Herrero, Mekanphotography and Joram Mennes.