Listen… (ooo, waa, ooo) …do you want to know a secret?
Okay seriously, with apologies to The Beatles, the Yucatan Peninsula is hiding miles and miles of secret rivers.
This was revealed to us just outside the Riviera Maya town of Playa del Carmen, Mexico when we descended beneath the surface and into Rio Secreto.
By into, we really mean in to.
Allow us to explain about this most unique spelunking experience.
Although the cave is ancient, it wasn’t discovered until 2006 when the property owner chased an iguana into a hole and heard a splash.
Curious, he dug a bigger opening and happened upon over twelve kilometers of underground river flowing to the Caribbean Sea. After a couple of years of work mapping and exploring, he decided to open the amazing tunnels to the public–as long as precautions were taken to protect it.
We are by no means experts when it comes to cave explorations — yes we have been down a hole or two (both literally and figuratively) — but never anything remotely close to this.
Certainly not any that required donning a wetsuit. Yet even in the tropical Yucatan jungle we were sure glad we suited up, the water in this underground stream never sees the sun so it is cool enough that skinny dipping was hardly an option.
Right, let’s pretend that is why we don’t skinny dip anymore.
Once we had wriggled into our second skins, we showered to make certain no chemicals from sunscreen or makeup could contaminate the pristine system below us.
This is just one of the many precautions Rio Secreto’s operators take to ensure the protection of the fragile formations and wildlife that occupy the cave.
Everyone involved with these tours views this as an ecological preserve, so the goal is not only to introduce this amazing underworld to people, but to conserve it for the future.
In addition, we were issued water shoes and a life vest, so that we could effortlessly drift along.
Lastly, we were fitted with an ultra-cool, light-weight, modern version of the old miner’s helmet. Our new-fangled head gear came with super bright LED lights.
Later we would learn what the cave would be like without those lights. Let’s just say that we would still be down there because we would never have found our way out.
As much as the attire was appreciated once we were in the water, it wasn’t high on our list of desirable outfits for trekking above ground.
Luckily that part of the journey was short. We walked a few hundred meters to the cave entrance and stopped for a ceremonial blessing honoring the Mayan traditions of rebirth associated with entering and exiting these sacred sources of life-sustaining liquid.
With our respects paid to the ancient traditions, our guide Paulo led us down into the darkness below. Our first discussion centered on how the cave and its features — the stalactites and stalagmites — were formed.
All of the land on this part of the Yucatan Peninsula is made of limestone, which at one time was an ancient coral reef. In fact, much of the walls of the cave still look like coral.
The limestone dissolves fairly easily, so the heavy tropical rains have carved out many of these long underground rivers, and even more cenotes, which are large, water-filled sinkholes.
These were incredibly important as water sources for the Mayans, and are still supplying drinking water today. Yet another reason for protecting the river from contaminants.
As for the classic cave features, stalactites and stalagmites, Paulo explained how they form over many years by dripping water.
As the water seeps through the stone it picks up calcium, which is then deposited little by little, leaving layers that create the eerie cones called stalactites that hang from the top of the cave.
When the drips fall, they form the matching rising cone shapes on the cave floor known as stalagmites.
There are a few tricks to remembering which is which; Paulo’s was that the T in stalactite stands for top, an old geology teacher told us “stalactites stick tight.” It worked, we still remember it.
After enough time, the two will meet with “a kiss” to form what is known as a column.
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Sometimes other forces, such as the capillary action of water being drawn along against gravity the same way a wick works, or changes in water levels, or wind can act on the formations to create strange and wonderful variations.
These cave features, known as speleothems, will appear as straws, which form when drops fall and leave a tiny ring behind, or curtains, which come from water slowly running down a slope.
Even rarer are helictites, which grow out like branches or fingers and seem to defy gravity, or the perfectly smooth gems known as cave pearls, which occur as drops roll a small stone in a pool.
Incredibly, every one of these was present in Rio Secreto.
We noticed another extremely interesting feature protruding from the ceiling of the cave, roots.
No plants can grow in the environment of total darkness, but roots from the trees dozens, sometimes even hundreds, of feet above have pushed their way through the stone in search of the precious water below.
The force and determination involved is truly amazing, and yet another example of life always finding a way to forge ahead.
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In keeping with that phenomenon, a few animals have managed to adapt to the lack of any light.
Bats, well-known cave dwellers, are fairly plentiful, especially near the openings that give them access to the outside world.
But even deep inside there some hardy residents. Crickets, ants, and a spider that has developed sensitive, antenna-like front legs for “seeing” in the dark, have all found a way to manage living deep underground.
Two types of fish, a small catfish, and the blind, colorless cave fish, inhabit the waters.
Paulo was very excited that we spotted both with our headlamps, since the cave fish are very rare indeed. The little white fish are not only blind, but over the eons they have completely lost their eyes.
No need for them, so they simply don’t grow any.
A little over halfway through the cave the water began to get deeper. Up until that point we had been anywhere from ankle to waist deep, but we would have to swim for it to go on.
Float for it might be more accurate, which was great. We rolled over on our backs, and down a lazy river we went, awestruck the entire way.
When we reached another shallow section, Paulo sat us down and introduced us to something most people have never experienced, total darkness.
We may think we have been in the dark, but no, there is almost always at least some tiny light source that our eyes can pick up and begin adjusting to.
Not this time. The complete, utter, absolute, unquestionable … okay, okay, point made, absence of any light whatsoever brought on a strange sensory deprivation that was somewhat unnerving. If we hadn’t known that we had the option to turn on our lights we probably would have freaked out.
Then a camera flash slashed through the darkness and shocked our vision.
Wow! It was so intense that we could see the bright outlines of the stalactites for several seconds. Paulo did it again, then again, and it was like a fireworks show inside our eyeballs.
There wasn’t going to be any topping that sensation, so with our lights back on, and our vision restored, we made our way up to the surface once again.
Back above ground we slithered out of our wetsuits and took a quick walk through the dry portion of the cave. This is an easy alternate route for those spelunkers who might not be comfortable with the total immersion version.
Best of all, it led to a mouthwatering buffet of local favorites.
Who knew spelunking could work up such an appetite?
David & Veronica, GypsyNester.com
We visited Rio Secreto while attending TBEX in Cancun, Mexico!
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YOUR turn: Isn’t it gorge-ous? Could YOU go down into an underwater cave in the total darkness?
In town Eddy tells us how the people of 
We sneak in some street food and grab a choclo con queso – yum! The cheese is unbelievably buttery.
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