The longest known underwater cave in United States is Wakulla – Leon Sinks cave system. The total length of explored cave passages here is 51,483 m. Between two entrances one should dive more than 11 kilometers and the distance (direct line) between the extreme ends of this cave system is 15.3 km. One of the highlights in this cave system is an impressive room – Black Abyss – which is 49 m high.

Floridan Aquifer

These caves, just as the other karst features of Florida, have formed in Floridan Aquifer. This aquifer consists of water-bearing limestones – more permeable than most other limestones elsewhere. In fact, this limestone is porous, like cheese, but with many fissures and tunnels. As water is passing through the limestone, the later is dissolved and cave systems are formed. In the upper reaches of these cave systems form sinkholes but in the lower reaches – powerful springs, which often discharge already under the sea level.

Woodville Karst Plain

Wakulla – Leon Sinks cave system has formed in Woodville Karst Plain – a region around Tallahassee and south from the city. This plain is very rich with sinkholes, submerged caves, and powerful springs. The limestone here was deposited in mid-Cretaceous – late Oligocene times.

Now the land here is located just a few meters above the sea level. Caves though go 106.7 m deep – far below the sea level. This is explained by the much lower sea level in the ice age – caves, for the most part, were formed then.

Leon Sinks

5 – 10 km northwest from from Wakulla Spring in the forest are found numerous sinkholes called Leon Sinks. Part of these sinkholes is located in Leon County, part – in Wakulla County. Some are enormous (Big Dismal is some 60 m deep), some smaller, some have small lakes at bottoms and some are dry.

Here starts the Wakulla – Leon Sinks cave system. Not all sinkholes now are leading into the cave – most likely the passages have been silted up, but quite many have connections to the cave. Some of Leon Sinks are listed below:

  • Big Dismal – wet sinkhole (with lake in it). This sinkhole is 30 m deep up to the water level and another 30 m deep below the water level. At 25 m depth is located the entrance in the cave system. Located at 30.315803 N 84.351568 W.
  • Black Gum – wet sinkhole. Located at 30.302703 N 84.352514 W.
  • Gator Sink – wet sinkhole. Located at 30.301025 N 84.351580 W.
  • Gopher Hole – dry sinkhole. Located at 30.308808 N 84.347690 W.
  • Gremlin Sink – wet sinkhole. Located at 30.301660 N 84.352945 W.
  • Hammock – wet sinkhole. Located at 30.314537 N 84.347152 W.
  • Turner Sink – wet sinkhole. Located at 30.265105 N 84.341432 W.

Rare crustaceans

In the cave system live numerous animals, including ones, which are endemic. One is Woodville Karst cave crayfish (Procambarus orcinus), which is not met outside Woodville Karst. This small crustacean lives in the silt of sinkholes and caves and its existence might be very endangered by the decreasing water quality.

Another endemic crustacean is the swimming Florida cave isopod (Remasellus parvus).

Research history

The courage and persistence of the explorers of Woodville Karst Plain caves is admirable. The exploration of these underwater caves has been technically extremely demanding and, unfortunately, has claimed many lives.

Research of the Wakulla cave system started in 1955 when 355 m long passages were explored.

Since then several expeditions have been organized and the underwater caves were explored step by step. This research always has been very dangerous and requires excellent organization of research itself and safety measures.

Culmination of this research took place on July 28, 2007. Two experienced cave divers of Global Underwater Explorer’s Woodwille Karst Plain Project – Jarrod Jablonski and Casey McKinlay – entered Turner Sink in the Leon Sinks and after 20 hours came out in Wakulla Springs. Dive itself took 6.5 hours, 14 hours were necessary for decompression after diving 90 m deep. There was no possibility to come to the surface in between – thus this was truly astounding accomplishment with a very complex support system.

Thus there were connected several large cave systems and the largest underwater cave system in the United States was discovered. Since then researchers have managed to extend the knowledge and now the known total length of passages is fantastic: 51,483 m!

By far not all is explored yet. Not too far is Chip’s Hole – more than 5 km long cave system and several more cave systems.


  1. The Woodwille Karst Plain Project by Global Underwater Explorers. Accessed on July 17, 2011.
Wakulla – Leon Sinks cave system on the map
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Location, GPS coordinates: 30.2651 N 84.3414 W (Coordinates of Turner Sink, which is approximately in the center of cave system)
Categories: Caves
Values: Geology, Visual
Rating: 4 out of 10 stars
Where is located? North America, United States, Florida, Leon and Wakulla Counties, between Leon Sinks, Wakulla Spring and area between Crawfordwille and St. Marks
Alternate names: Leon Sinks Cave system
Length: 51,483 m
Maximum depth: 106.7 m

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