El Zacatón cenote

Quick facts

• Location: Rancho La Azufrosa near Aldama, Tamaulipas, northeast Mexico (not the Yucatán).
• Depth: about 335 m total; the water column measured by the DEPTHX robot was over 300 m (reported).
• Width: roughly 110 m across (reported).
• Water: warm (about 30 °C) and sulfurous (reported).
• Status: private land; no public swimming.

How it formed

Unlike Yucatán cenotes, Zacatón is linked to volcanic activity. Warm, acidic, mineral-rich water rising from below is thought to have dissolved the limestone, forming a deep shaft. It belongs to a group of similar sinkholes nearby, such as El Verde, Caracol, Poza Azul and La Pilita (reported). The name comes from zacate, grass, after the floating grass islands that drift on its surface.

Record dives

• 1994: legendary cave diver Sheck Exley died here trying to reach the bottom, at around 270 m (reported).
• The same day, Jim Bowden reached about 282 m, a long-standing depth record (reported).
• Divers since have used it for deep scientific and technical dives.

NASA's DEPTHX robot (2007)

A NASA-funded autonomous robot called DEPTHX mapped Zacatón in 2007 to test technology for exploring oceans under the ice of Jupiter's moon Europa. It measured the depth and collected samples of microbes living in the dark water (reported).

Life in Zacatón

Purple and other colored microbial mats grow on its walls, and scientists studied microbes from the depths as a model for life on other worlds (reported).

Zacatón vs Yucatán cenotes

• Origin: volcanic hot water vs rainwater dissolving limestone.
• Water: warm and sulfurous vs about 24–25 °C and fresh.
• Access: private, no swimming vs hundreds of open visitor cenotes.
• Depth: one of the deepest known sinkholes vs most Yucatán cenotes are much shallower.

Can you visit?

No public swimming. If you want very deep cenotes you can visit, see How deep are cenotes and the Yucatán profiles in our directory, like Sabak-Há.