What is cenote diving?

When cenote diving, you dive into water-filled caves on the Yucatán Peninsula in Mexico, but only as far as daylight from the entrance reaches. A cave-trained guide leads you along a permanently installed line, and for most cenotes, your open-water certification is sufficient. Diving takes place mainly in the hinterland of the Riviera Maya between Puerto Morelos and Tulum; from Cozumel, you can reach them in a day by ferry.

What is a cenote?

The word comes from the Mayan tz’onot, meaning spring or abyss. It refers to an opening in the karst where groundwater is exposed. Long underwater caves run beneath the coast of Quintana Roo, and the cenotes are their entrances. In Quintana Roo, collapsed cenotes are very common. They were formed when the sea level fell and the water no longer supported the ceilings of shallower caves. This is how geologists Kambesis and Coke describe the Sistema Sac Actun, one of the longest underwater cave systems in the world.

There are two layers in the groundwater. On top, a thin lens of rainwater flows toward the coast. Below it is saltwater pushing in from the sea. The boundary layer between the two is called the halocline, and when you dive through it, visibility blurs for a few seconds. The freshwater remains at 24 to 26 °C all year round, and waves and sargassum do not reach it.

Where are cenotes located?

The Yucatán Peninsula is a large karst area with many cenotes, and most have a connection to the sea. Several of the well-known cenotes are located around Tulum. Dos Ojos is located about 25 minutes north of the city, El Pit 3 km further back in the same park, Casa Cenote in the mangroves of Tankah, and Angelita south of Tulum. Chac Mool is located just behind Puerto Aventuras, about 23 km south of Playa del Carmen.

There are also cenotes on Cozumel; Cenote Aerolito, for example, is a pool between mangroves connected to the Caribbean via channels and passages. However, for a cenote day, you take a ferry from the island to the mainland. You take the 7 a.m. ferry to Playa del Carmen, the base picks you up at the pier, and you return by ferry at 4 or 5 p.m. You pay for the ferry ticket yourself.

How a cenote dive works

The day begins between 7:30 and 8:30 a.m. with pickup at the hotel or the base; the drive takes up to an hour. After the briefing, two dives of around 45 minutes follow, with a break in between; you are back around 3 or 4 p.m. Because the light falls most beautifully through the openings in the early morning, around 8 a.m. in Kukulkan, most bases dive in the morning.

Underwater, you stay in the cavern, the daylight zone. You always see light from the entrance, a continuous line leads back to the open water, and the next surface with air is at most around 60 m away. You do not dive through narrow passages where two divers cannot fit side by side. A guide leads at most four divers, and three at Under the Jungle. He is a dive instructor and cave diver. You dive in your normal equipment with a base lamp that burns for the entire dive. After one-third of your gas, you turn back, as required by the rule of thirds.

Requirements and rules

The rules in the cenotes are set by the bases; no authority publishes any. For most cenotes, open water is sufficient. For the deep shafts El Pit and Angelita, the bases require Advanced Open Water. You do not need your own cavern certification as long as you are guided by a cavern guide. Your last dive should not have been too long ago. Scuba Tulum takes you with a maximum break of one year, Under the Jungle after a maximum of six months and with at least 20 logged dives. Several bases recommend a dive in the sea before the first cenote. The bases take divers from age 15.

In 21 percent of just under 1,000 fatal sport diving accidents analyzed by DAN, a diver was trapped under a ceiling and could not return to the open water. Beyond the daylight zone, cave diving begins, and for that, you need your own training.

Without a dive certificate, a base in Mexico will only take you on a try-out dive according to the NOM-012-TUR-2016 standard. In the open parts of Dos Ojos, you can snorkel. Before entering, sunscreen and insect spray on the skin are prohibited at Scuba Tulum and Under the Jungle. The cenotes are located on private land; you usually pay the entrance fee in pesos in cash at the entrance, and almost all charge a fee for your own camera. For two dives, Pro Dive and Under the Jungle recommend a long 5 mm suit.

Well-known cenotes

The bases call Chac Mool one of the best cenotes for beginners. You stay at around 12 m, dive in an air pocket with stalactites on two levels, and see the halocline at 8 to 10 m. Dos Ojos is shallow. The Barbie Line stays at 6.5 to 7 m and is bright; in the darker Bat Cave, bats hang from the ceiling in an air pocket. El Pit is a shaft around 119 m deep. On a guided dive, you dive to at most 30 m, where a cloud of hydrogen sulfide lies in the water. Angelita is also an open shaft with a cloud at 30 m; Casa Cenote is a coastal cenote between mangroves.

Portraits of Chac Mool, Dos Ojos, and El Pit with directions, entry, and depths are in the Cozumel and Cenotes Dive Atlas.