Boardwalk at Madison Blue Spring State Park

Madison Blue Spring cave system

Spring system7.9 km surveyedUnited States, Florida

Photo: Michael Rivera · CC BY-SA 4.0

Open to qualified divers, with conditions · as published 2026-10-14 Managed by Florida State Parks. Certified cave and cavern diving only; divers sign in at the boardwalk, dive in pairs or larger teams, may not use scooters and must finish an hour before sunset. Access rules change: confirm with the landowner or managing authority before you travel.

Well documented Also known as: Madison Blue, Madison Blue Spring, Madison Blue Springs, Blue Spring (Madison County), Madison Blue Spring State Park

Surveyed length

7.9 km (2014)

Documented depth

Not published

Entrances listed

Water temperature

22 °C

Over 26,000 feet of passage explored, as cited by Florida State Parks from Gulden and Coke (2014). The park pages do not say who conducted the survey.

A first-magnitude spring on the Withlacoochee River whose underwater cave, entered about 9 metres below the pool surface, has more than 26,000 feet of mapped passage; certified cavern and cave diving only.

Madison Blue Spring rises into a limestone basin on the west bank of the Withlacoochee River in north Florida, inside Madison Blue Spring State Park. The pool is about 25 metres across and 7.5 metres deep and drains down a short run into the river. It is a busy swimming hole in summer as well as an internationally known cave-diving site.

About 30 feet (9 metres) below the surface of the pool, a large opening leads into the cave. Florida State Parks reports that certified cave divers have mapped more than 26,000 feet of passage, citing a 2014 survey compilation, which places it among the longest underwater caves in Florida. The passages extend beyond the park boundary and pass beneath the Withlacoochee River just south of the State Road 6 bridge. Martz Sink, also in the park, gives a second way into the system.

The park allows certified cave and cavern diving only; there is no open water diving or freediving with scuba here. The caves are home to three cave-dwelling crustaceans that depend on stable aquifer conditions: the pallid cave crayfish, Hobbs' cave amphipod and the swimming little cave isopod.

Geology

The spring water comes from the Oligocene Suwannee Limestone, the uppermost formation of the Floridan aquifer system in the park, a white to cream fossil-rich limestone that crops out in the spring and the river. Around the spring it is overlain by sands and clays of the Miocene Torreya Formation and the Pliocene Miccosukee Formation. The fossil sea biscuit Rhyncholampas gouldii, an index fossil for the Suwannee Limestone, is common in local outcrops.

Water, flow and flooding

Madison Blue is a first-magnitude spring, meaning it discharges at least about 2,800 litres (100 cubic feet) per second. Florida State Parks says the outflow pushes into the Withlacoochee River and sweeps a clear arc across the river bottom. The park lists many sinkholes as evidence of a close connection between surface water and the aquifer.

Why it matters

One of the longest mapped underwater caves in Florida, and habitat for three imperilled cave crustaceans. Florida State Parks describes the park as protecting nationally significant examples of karst topography.

Conditions

The spring averages a steady 72°F (22°C). The park closes when it reaches capacity, which often happens between 10 a.m. and 3 p.m. on weekends and holidays. Effective 2026-10-13 the park announced it was closed to swimming; the notice did not mention diving.

Typical ranges from published sources, not current conditions.

Entrances and dive sites

The main entrance is a large opening about 30 feet below the surface of the spring pool. Florida State Parks also describes diving from Martz Sink in the park. The cave extends outside the park boundary.