NBM Dive Site Resource
Mermet Springs
Belknap, Illinois, United States
An 8.5-acre spring-fed quarry and full-service scuba training facility in southern Illinois, serving new divers through advanced, technical, public-safety, and professional training. Mermet Springs combines multiple depth zones, easy-entry docks, accessible entry assistance, abundant freshwater life, and an unusually large collection of submerged aircraft, vehicles, navigation challenges, and other attractions.
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Featured Hero Photograph
Aquatic life at this dive site
What divers may encounter
Three reviewed connections are featured here. Sightings vary by season, conditions, and chance, so they are never guaranteed.
American Paddlefish
Polyodon spathulaSchools of paddlefish are a defining Mermet Springs encounter, although sightings still depend on conditions and the route dived.
USFWSOpen Aquatic Life Profile →
Bluegill
Lepomis macrochirusLarge bluegill are reported in the quarry's freshwater habitat.
USFWS Mountain PrairieOpen Aquatic Life Profile →
Freshwater Jellyfish
Craspedacusta sowerbiiSmall freshwater jellyfish are reported at Mermet Springs, but encounters are uncommon and seasonal.
Павлик ЛисицынOpen Aquatic Life Profile →
Site media
Photographs
Three views rotate from the published gallery on each visit.View 4 additional photographs →
Contributor media
Dive videos
Three featured video positions are reserved on every profile.Published reference location
Location map
The marker shows the public coordinates associated with this profile. Confirm current access, moorings, and departure details before the dive.Map data © OpenStreetMap contributors
Official conditions
Current temperatures
Automatically checked twice daily. The most recent successful reading remains visible if the source is temporarily unavailable.Source updated Nov 6, 2026 · Last checked Nov 10, 2026, 6:05 PMMermet Springs ↗
Why divers know this place
Highlights
The 120-foot Boeing 727 fuselage used in the film U.S. Marshals, with its nose at roughly 50 feet and an open-hatch swim-through; railroad coal car at 55 feet; human-powered submarine at 60 feet; Ford pickup at 60 feet; Cessna aircraft at 55 feet and 40 feet; ambulance at 45 feet; firetruck at 50 feet; semi-truck at 30 feet; divecache at 60 feet; cabin cruiser at 40 feet; motorcycle and concrete petting zoo at 12 feet; Bruce the Shark at 8 feet; underwater bike-navigation trail; underwater forest; paddlefish, freshwater jellyfish, catfish, and other freshwater life.
Quarry-only module
Quarry layout and services
This section appears only for quarries and mines, with the practical details divers need for entries, training areas, submerged features, surface support, and current operations.
- Former use
- Spring-fed stone quarry developed into an 8.5-acre full-service scuba training and recreation facility
- Current operating status
- Open year-round on seasonal hours. June–October includes evening diving until 10 p.m. on Friday and Saturday; November, winter, and spring use reduced schedules. Additional hours may be arranged with advance notice.
- Entry points
- Four designated easy-entry docks offering walk-in, giant-stride, and controlled seated entries; primary dock has an accessibility lift
- Training platforms
- Multiple platforms at 5, 15, 20, 65, 85, and 100 feet
- Submerged attractions
- Boeing 727 swim-through with nose near 50 ft; railroad coal car 55 ft; pedal submarine 60 ft; Ford pickup 60 ft; Cessna 55 ft; Cessna 152 40 ft; ambulance 45 ft; firetruck 50 ft; semi-truck 30 ft; divecache 60 ft; cabin cruiser 40 ft; motorcycle and concrete petting zoo 12 ft; Bruce the Shark 8 ft; underwater bike trail and underwater forest.
- Onsite dive services
- Try Scuba through instructor-level training, guided quarry dives, full equipment and drysuit rentals, air and custom Nitrox fills, equipment inspection and repair, quarry maps, and instructor/group support. Published guide fees at review were $25 first dive, $20 second, and $15 third, excluding admission, rental, and fills.
- Surface facilities
- 18 covered waterfront pavilions with electricity, lights, and fans; heated showers and restrooms; Snack Shack; parking and staging. Tent sites are first-come-first-served. Reservable RV sites provide 30-amp power but no potable water or sewer.
Before you arrive
Access notes
Every diver and non-diver must complete the current digital site release and check in at the office each day. The operator listed daily admission of $25 for divers and $8 for non-divers when reviewed on October 23, 2026; confirm current pricing before travel. Divers must present a certification card or be accompanied by an instructor. Solo diving is prohibited. Use designated entry points and dive only during business hours while staff are on duty. General swimming, alcohol, pets, fishing, spearfishing, and portable compressors or cascade systems are prohibited; snorkeling requires a BC or PFD. Diving below 80 feet calls for appropriate training, cold-water equipment, redundancy, or direct instructor supervision.
Plan within your training
Conditions and hazards
Cold deep water near 42°F, pronounced thermoclines, depths beyond 80 feet, variable visibility, submerged structures, swim-through and entanglement hazards, and possible regulator free-flow in cold water. Stay within certification and experience limits, carry suitable thermal protection and equipment, use the buddy system, follow marked routes and restricted areas, and review the site rules and Emergency Action Plan.
At the site
Facilities and support
Four easy-entry docks with walk-in, giant-stride, and seated-entry options; the primary dock includes an accessibility lift. Multiple platforms sit at 5, 15, 20, 65, 85, and 100 feet. The site has 18 reservable waterfront pavilions with electricity, lights, and fans; heated showers and restrooms; full recreational rental inventory including more than 50 drysuits; air and custom Nitrox fills; equipment inspection and repair; quarry maps; Snack Shack food service; and instructor/group support. Guided tours were listed at $25 for the first dive, $20 for the second, and $15 for the third when reviewed, excluding admission, rentals, and fills. First-come tent camping and reservable 30-amp RV sites are available; RV sites have no potable water or sewer.
Independent resource notice
This record is a starting point for independent verification. Access, closures, moorings, weather, currents, depth, visibility, operator availability, and site conditions can change without notice. Confirm current information with the responsible operator, property owner, managing authority, or another qualified local source before planning or attempting a dive.