Florida
Mill Creek Sink (Alachua Sink)
Info · exploration
Information only: Mill Creek Sink is an NSS nature preserve. Only qualified cave divers may go in, and only for research, data collection, water sampling or survey, after approval and with a permit.
- Max depth69 m (226 ft)
- CertificationFull cave
- SpecialExperienced divers
Diving and fills
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Fills nearby
- Extreme Exposure (High Springs)Air, nitrox (32 %, 50 %), O₂ (AL40) and trimix ('mix' in doubles); walk-in fills of your own tanks: ask
- Cave Country Dive Shop (High Springs)Air, nitrox 32 % and 50 %, O₂, helium; trimix 21/35, 18/45, 10/70 and custom; CCR O₂ fills
- 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)
Now at Mill Creek Sink (Alachua Sink)
The dive
You descend a steep slope to a basin full of fallen trees and debris. The water is dark and tannic for most of the year, and clear water is only reached well into the cave.
Profile and sections
You descend a steep slope to a basin full of fallen trees and debris. The water is dark and tannic for most of the year, and clear water is only reached well into the cave. Downstream there is strong siphon flow, and shallower sections can act as a decompression ceiling. The formations and clay banks are fragile.
Mill Creek Sink is the only known accessible window to the underground Mill Creek stream system. More than ten swallow holes take the creek underground, from a basin of over 180 km². Dye traces by the NSS-CDS in 1976 and 2006 linked the sink to Hornsby Spring, ~10 km away, which feeds the Santa Fe River. The NSS was given the land in 1993; members of KUR and the NSS-CDS helped map the cave.
Practical: a preserve for research, with the occasional alligator; without the NSS's approval you cannot dive here.
- Depth and profile
- Down to -69 m (the NSS-CDS gives deeper than -61 m downstream) · restriction at ~-58 m downstream · over 450 m of passage
- Configuration
- No configuration rules published; restrictions make it an advanced dive.
- DPV: unknown
- Research only; no scooter rules published.
- Gas
- Trimix from 40 m (131 ft)
Who can dive where
- At least Full cave
- Configurations: Backmount / twinset / Sidemount / CCR
- Goes down to 69 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
In the city of Alachua. A steep slope drops ~15 m to the water. The NSS-CDS manages the diving: NSS and NSS-CDS membership, full cave, the Abe Davis Award (100 cave dives) or equivalent experience, three logged cave dives to ~-46 m with 45+ minutes of deco, gas certification for beyond ~-40 m, DAN insurance (or equivalent) and a waiver on the day. Always with an approved guide, max. two divers per guide; three upstream dives first before the downstream tunnel. No training, no commercial dives and nobody charges a fee.
Around Mill Creek Sink (Alachua Sink)
Fills3 fill stations · nearest 0 km
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.
Cave Country Dive Shop (High Springs)
19808 N US Hwy 441, High Springs, FL 32643
Air, nitrox 32 % and 50 %, O₂, helium; trimix 21/35, 18/45, 10/70 and custom; CCR O₂ fills
Daily 7:00–19:00
Prices per cu ft online (e.g. 18/45 $2.04, 10/70 $3.15, O₂ $0.50; CCR O₂ min. $6). Rentals: backmount/sidemount doubles $14/day, trimix bailout cylinder $16, SUEX scooter $85/day, Shearwater computers. Cave courses from cavern to full cave and CCR cave (TDI, IANTD, NSS-CDS) by the owner's BJL Diving, and guided cave and spring dives, also with scooter, CCR, trimix and stages.
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.
Drive times from High Springs: we don't know this site's exact spot.
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