Cenote, a type of freshwater sinkhole usually found in Yucantan Peninsular and some nearby Carribean islands. A term derived from low land Maya to refer to any location that has access to groundwater.
(with reference to wiki)
the above is one type of cenote.
Im hooked onto the Maya underworld, but im not sure if im brave enough to explore it, if i ever could.

ok, this is damn cool. the cloudy stuff is actually sulphurous cloud caused by decomposing matter. It actually looks like the ground so divers might thought they are landing but eventually, they sink through it into the heavier saltwater beneath the freshwater above the cloud.

ok! go search up on it. im going off to play mahjong.
nite!