A cenote is a natural phenomenon, a sinkhole in the Earth’s surface. Nearly everyone who visits the Yucatan Peninsula soon learns of this rather unique feature of the local landscape.
National Geographic listed "Dive Caves in the Yucatan" a must-do trip of their Ultimate Adventure Bucket List 2012
After my Cancun's Underwater Museum dive, cavern/cenote diving was next on my Bucket List.
Cave diving and cavern ( cenote ) diving are two different things. In short, you need the proper training and equipment for cave diving.
But for cenote diving all you need is an open water certificate.
The Yucatan Peninsula in Mexico has an estimated 7,000 cenotes, but only a dozen of them are open to recreational divers. There are a few companies and several dive stores that offer exciting excursions to some of the most beautiful cenotes close to Cancun and Playa del Carmen. My choice was The Reef Marina Dive Shop
One of the more popular in the area (due to proximity to Playa del Carmen), Chac Mool cenote has something for everyone from speolotherms galore and airdomes on the cavern tour to long penetration cave dives in both directions. But most important, it's a perfect beginner dive site !
I'm not even going to try to describe all the beauty and excitement of cenote diving ! You have to experience it for yourself. So far, this has been my ultimate diving experience ! Such a novelty can only be experienced; pictures and descriptions don't do it justice. Cenote diving is a mind blowing adventure, and I guarantee you, you'll come up to the surface speechless !
CENOTE DIVING IS NOT RECOMMENDED FOR DIVERS WITH CLAUSTROPHOBIA
Though, in a cavern, you are always within sight of natural daylight, there are certain areas where you feel your mind playing tricks on you. Sometimes the closed in cave-like atmosphere can give those with claustrophobia real problems and the overhead restrictions of cavern diving demand good buoyancy control.
Also,Chac-Mool is one of the caverns which has a Halocline - his is where salt and fresh water come together creating "fascinating" visual effects. It gets blurry, so don't freak out, you're not loosing your mind :)
But all in all, diving in a cenote is very different from ocean diving and must truly be experienced to be fully appreciated. Divers who have floated through this amazing world will remember it forever !