Types of cenotes

Quick answer

Cenotes are grouped by how much of the cave roof has collapsed. Over time a cave cenote becomes semi-open, then open, then an old shallow pool. That is why guides often call them young, middle-aged and old cenotes.

1. Cave (closed) cenotes

Fully or almost fully underground, entered by stairs or a small hole. Water is very clear and calm, light is dim, and you often see stalactites. Also called cavern or 'young' cenotes.

• Examples: Calavera (Tulum), Dos Ojos, Suytun, Kankirixché, Xkeken.
• Good for: snorkeling, light beams, photography.
• Watch out: low light, slippery steps, bats.

2. Semi-open cenotes

Part of the roof has fallen in, so there is a large opening with a rock ceiling over part of the water. Light, vines and roots come in from above.

• Examples: Ik Kil, Samula, Gran Cenote, Hubiku.
• Good for: swimming with dramatic views and light.
• Watch out: busy at midday.

3. Open cenotes

The roof is gone, leaving a round, open pool with steep walls. They are bright, warmer at the surface and often have plants and fish.

• Examples: Zací (Valladolid), Cenote Azul (Playa del Carmen area), Casa Cenote, Cristalino.
• Good for: families, sunbathing, easy swimming.
• Watch out: sun; no sunscreen allowed.

4. Ancient (old) cenotes

Very old cenotes whose walls have worn down until they look like ponds or lagoons, often with sediment and plants. Some scientists also describe 'aguada' type cenotes like this (reported).

Other ways cenotes are classified

• By shape, scientists use four classic forms: jug or pitcher-shaped, cylinder, open bowl and cave (reported, Wikipedia).
• By water: freshwater only, or with a halocline where saltwater sits below.
• By access: swimming cenotes, snorkel cenotes, dive-only cenotes and private or sacred ones.
• By location: inland (Yucatán, Valladolid) vs coastal (Tulum), where cave systems connect to the sea.

How cenotes change type over time

• Rainwater, slightly acidic, dissolves limestone and opens a cave.
• During the ice age, sea level was much lower and caves were dry; stalactites formed then.
• As the roof thins, parts collapse and a cave becomes semi-open.
• With more collapse it becomes open, and slowly fills with sediment as an old cenote.

Which type should you visit?

• Non-swimmers and kids: open cenotes with life jackets and shallow edges.
• Photographers: cave and semi-open cenotes at midday.
• Snorkelers: clear cave cenotes like Dos Ojos.
• Divers: cavern dives in Tulum-area systems with a certified guide.

Anchialine cenotes

Scientists also use the word anchialine for cenotes linked to the sea underground. They have fresh water on top and salt water below, with a halocline between. Most cenotes near the Caribbean coast, such as those around Tulum, are of this kind, while inland cenotes near Mérida and Valladolid hold mostly fresh water.