Florida · about 16 km from Live Oak
Falmouth Spring (Falmouth–Cathedral system)
Info · exploration
Information only: the NSS-CDS closed access in 2014. Since then only Karst Underwater Research (KUR) dives here, under permits from the Suwannee River Water Management District and the NSS-CDS, for exploration and survey.
- Max depth56 m (184 ft)
- CertificationFull cave
- SpecialExperienced divers
Diving and fills
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Fills nearby
- Amigos Dive Center (Fort White)Air to 4,500 psi (~310 bar), nitrox 21–40 %, medical O₂ (also for rebreathers), custom trimix (continuous blender), argon
- Ginnie Springs dive shopAir (high-volume) and nitrox 32 %; no trimix listed. Prices 2026, excluding tax: air $9, doubles air $14, nitrox single cylinder $15, nitrox $0.15 per cubic foot (for top-offs and doubles)
- Extreme Exposure (High Springs)Air, nitrox (32 %, 50 %), O₂ (AL40) and trimix ('mix' in doubles); walk-in fills of your own tanks: ask
Now at Falmouth Spring (Falmouth–Cathedral system)
The dive
A deep river cave with a main trunk over 12 m wide and visibility averaging 3 to 6 m. The depth changes constantly, which costs extra gas.
Profile and sections
A deep river cave with a main trunk over 12 m wide and visibility averaging 3 to 6 m. The depth changes constantly, which costs extra gas. Recent exploration dives lasted more than 400 minutes at an average of ~-46 m, with heavy decompression.
The main conduit runs from Cathedral Canyon Sink to Ellaville Springs on the Suwannee, with several karst windows along the way; dye traces show a connection to the Edwards-Suwanacoochee system. Sheck Exley got more than 3.3 km in in 1990; exploration then stopped until 2003. Todd Leonard and Bjarne Knudsen pushed more than 5.2 km from Cathedral between 2003 and 2005. After years of drought, with the spring reduced to a trickle, and the 2014 closure, KUR took up the work from 2015: ~2.1 km of line replaced, safety bottles at 670, 1370, 1830 and 2440 m and a decompression habitat in Cathedral Sink. On 4 November 2016 the team set a record of 8.2 km penetration from air from Cathedral Canyon. The system now has ~10.2 km of surveyed passage.
Practical: information only; swimming is possible in the spring on the water district's land.
- Depth and profile
- Plan for more than -56 m: deeper than -56 m in places, average ~-46 m, shallowest ~-21 m (KUR elsewhere lists -49 m as the maximum) · 10.2 km surveyed
- Configuration
- Expedition dive with long decompression; no configuration for visitors known. The main trunk is over 12 m wide.
- DPV: unknown
- Not open to visiting divers.
- Gas
- Trimix from 40 m (131 ft)
Who can dive where
- At least Full cave
- Configurations: Backmount / twinset / Sidemount / CCR
- Goes down to 56 m (trimix or deco may be needed)
- Experienced divers only
This is how the planner decides who in your team may dive this cave. Rules your own trip adds (organizer, a mail, the AI) show with your trip.
How to get there
Falmouth Spring lies on Suwannee River Water Management District land near Falmouth (Suwannee County), open for swimming. The cave is not open to visiting divers.
Around Falmouth Spring (Falmouth–Cathedral system)
Fills3 fill stations · nearest 63 km
Amigos Dive Center (Fort White)
5472 SW Elim Church Rd, Fort White, FL 32038
Air to 4,500 psi (~310 bar), nitrox 21–40 %, medical O₂ (also for rebreathers), custom trimix (continuous blender), argon
During shop hours (times not listed) — ask
Walk-ins welcome. O₂-clean equipment required for O₂. Dive centre in 'cave country' since 2006.
Ginnie Springs dive shop
Ginnie Springs Outdoors (in the park), near High Springs, FL
Air (high-volume) and nitrox 32 %; no trimix listed. Prices 2026, excluding tax: air $9, doubles air $14, nitrox single cylinder $15, nitrox $0.15 per cubic foot (for top-offs and doubles)
Park hours: Mon–Thu 8:00–17:00, Fri–Sat 8:00–19:00, Sun 8:00–18:00. Last fill between 15:00 and 17:00, depending on the fill technician's availability
Rents cylinders (incl. nitrox steel 85), BCs, regulators, suits and lights. Personal compressors are banned in the park.
Extreme Exposure (High Springs)
18481 High Springs Main Street, High Springs, FL 32643
Air, nitrox (32 %, 50 %), O₂ (AL40) and trimix ('mix' in doubles); walk-in fills of your own tanks: ask
Daily 8:00–18:00
Tech and cave shop since 1995. Rents singles, stages and doubles (steel/alu, air, nitrox or mix), regulators, backplate/wing, lights and scooters; training.
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