The Yucatán Peninsula has almost no rivers. Its fresh water flows underground through limestone, and where a cave roof collapses the water appears in a cenote: a natural well of clear blue water, sometimes open to the sky and draped with roots, sometimes hidden in a cavern lit by a single shaft of sunlight. Mexico's peninsula holds at least 6,000 of them, and swimming in one is a highlight of any trip to Yucatán and Quintana Roo.

Open cenote in Yucatán with hanging roots, green vegetation and swimmers in blue water
Photo: BORIS G.

What is a cenote?

The word comes from the Yucatec Maya ts'onot, a place with accessible groundwater. The peninsula is a vast slab of porous limestone. Rainwater soaks straight through it and slowly dissolves the rock, carving cave systems that fill with water. When a roof weakens and falls in, the water table is exposed as a sinkhole.

Underground, fresh rainwater floats on denser salt water that seeps in from the sea. The boundary, the halocline, lies about 10 to 20 metres below the water table near the coast and 50 to 100 metres down inland; divers crossing it see the water shimmer and blur. Many cenotes connect to huge flooded cave networks. Sistema Sac Actun near Tulum, linked to the Dos Ojos system in 2018, has more than 370 km of mapped underwater passages and ranks among the longest underwater caves on Earth. In its Hoyo Negro pit, divers found the skeleton of a teenage girl known as Naia, one of the oldest human remains in the Americas.

Cave cenote with turquoise water, hanging stalactites and swimmers lit by lamps
A cavern cenote with stalactites and lights above the water.

The Ring of Cenotes and the Chicxulub crater

On a map, the cenotes of northern Yucatán trace a striking arc around the town of Mérida. This Ring of Cenotes sits over the buried rim of the Chicxulub crater, left by the asteroid impact about 66 million years ago that ended the age of the dinosaurs. Fractures in the rock around the crater's edge guide groundwater and make collapses more likely there.

Cenotes in Maya history

For the Maya, cenotes were both water supply and sacred doorways to the underworld, Xibalba, and the realm of the rain god Chaac. Cities such as Chichén Itzá grew up beside them. From 1904 the American Edward Herbert Thompson dredged the Sacred Cenote at Chichén Itzá and recovered human skeletons, jade, gold and other offerings, evidence of sacrifice to the rain god. Practices varied from place to place, though: at Punta Laguna, researchers studying about 120 individuals found no signs of sacrifice at all.

Sunlight falling into a deep cenote surrounded by stone walls and hanging roots
Photo: BORIS G.

Cenotes worth visiting

  • Ik Kil, near Chichén Itzá outside Pisté: an open cenote about 60 metres across, with the water some 26 metres below ground and about 48 metres deep. A carved stairway leads down to a swimming platform, and long roots hang to the water. Red Bull Cliff Diving held World Series events here in 2010, 2011 and 2014. It pairs easily with a morning at the ruins.
  • Zací, in the middle of Valladolid: a large, partly open cenote you can walk to from the town square.
  • Samulá and Xkekén (Dzitnup), just outside Valladolid: two cavern cenotes where sunlight and tree roots enter through a hole in the roof.
  • San Ignacio, in Chocholá, and Sambulá, in Motul: quieter cenotes within easy reach of Mérida.
  • Dos Ojos, north of Tulum: famous for snorkelling and cavern diving in exceptionally clear water.
Swimmers in a cenote pool beneath a curtain of long hanging roots
Roots reaching down to the water in an open cenote.

Tips for swimming in a cenote

  • Go early. Popular cenotes near Chichén Itzá and Tulum fill with tour groups from late morning.
  • Shower first, skip the sunscreen. Most sites require a rinse before entering and ban chemical sunscreen and repellent, which pollute the aquifer that supplies the peninsula's drinking water.
  • Bring cash and water shoes. Many smaller cenotes charge a modest entry fee in pesos, and steps and rocks can be slippery.
  • Wear a life jacket if you're not a strong swimmer; most sites rent them, and the water is deep.
  • Leave cave diving to the certified. Cavern tours with a licensed guide let snorkellers and open-water divers see the underground passages safely.
Semi-open cavern cenote with blue water, rock ledges and visitors on stone steps
A partly covered cenote with steps down to the water.

Plan a cenote swim alongside Chichén Itzá, or base yourself on the coast with our Tulum guide. Ik Kil's own website lists current hours and prices.

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