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Underwater cave system
Sac Actun
Tulum, Quintana Roo, Mexico
No public photo available
The longest known underwater cave system in the world, which links cenotes to the Caribbean Sea.
40 m
119 mRecreational limitBathymetry and profile
Mostly shallow passages 5-20 m deep. Below about 15 m there is a layer where fresh water floats on salt water. The pit of Hoyo Negro reaches 57 m and holds Ice Age bones.
Dashed line: 40 m recreational diving limit
Features
- Layer where fresh water meets salt water
- Ice Age remains, including 'Naia', one of the oldest known humans in the Americas
- Stalactites and stalagmites under water
Specific fauna
- Blind cave fish
- Cave shrimp
- Remipedes (ancient crustaceans)