[4] The numerous deep vents at the bottom of the sinkhole feed oxygen-depleted groundwater into it, producing an anoxic environment below a depth of about 5 m (16.4 ft).

[4] This fosters the preservation of Paleo-Indian and early Archaic artifacts and ecofacts, as well as fossil bones of the extinct megafauna once found in Florida.

[5][6][7] Little Salt Spring was considered a shallow freshwater pond, but in 1959 SCUBA divers William Royal and Eugenie Clark discovered that it was a true sinkhole extending downward over 200 ft (61 m),[4][8] similar to the cenotes of the Yucatán Peninsula (another karst region).

Twelve to thirteen thousand years ago the ocean level was about 100 meters (more than 300 feet) lower than at present, drawing down the water table in Florida, and the water level in Little Salt Spring was 27 meters (89 feet) lower than at present.

As has happened in other wetland burials in Florida, such as at the Windover Archaeological Site, brain matter survived in many of the skulls.