How deep is Mermet Springs?

Mermet Springs has a depth range of 4.6–36.6 metres (15–120 feet). Check the dive site page for current conditions and any depth-specific guidance before planning your dive.

Can beginners dive Mermet Springs?

Mermet Springs is rated as advanced difficulty, which may not suit new divers. A Open Water; wreck/overhead training for 727 penetration; deep/tec training below 60 ft certification or equivalent is suggested. Consider your experience level, conditions, and local guidance before planning.

When is the best time to dive Mermet Springs?

The best time to dive Mermet Springs is typically Spring and fall for best visibility. Conditions vary, so check the latest reports and forecasts on the dive site page before your trip.

What will I see at Mermet Springs?

Divers at Mermet Springs in United States commonly report sightings of Paddlefish, Blue catfish, Largemouth bass, Bluegill, and Grass carp. Marine life varies by season and conditions—check the site page for recent diver observations and photos.

Add the first photo

AdvancedShore entry

Mermet Springs

Illinois, United States

Open Water suggested5–37 m depthShore entry

Mermet Springs at a glance

Mermet Springs is a advanced shore dive site in Illinois, United States with depths of 4.6–36.6 m (15–120 ft). Typically most favorable Aug · from 3 years of archive data. Divers commonly see Paddlefish, Blue catfish, and Largemouth bass. Check the latest conditions and entry details before you go.

Wind model · graded 4h ago

—

Tap a factor for its source and model point

Site hazards: Deep dark water below the thermocline, overhead environment inside the 727 fuselage (training required), entanglement on attractions, low visibility after heavy rains

Read the full hazards ↓

Dive windows this week

Best: Fri

Sun6:00–21:00

Mon6:00–10:00

Tue6:00–21:00

Wed6:00–21:00

Thu6:00–21:00

Fri6:00–21:00

Sat7:00–21:00

Favorable windowModerate window— no window

First light 5:26 · Sunrise 5:55 · Sunset 20:08

Source: Open-Meteo wind · graded 4h ago

Forecast only — always assess conditions on site.

Recent diver reports

Dated firsthand observations from divers — not current conditions.

No diver reports for this site yet. — one dated observation helps every diver after you.

What Divers Say

Known for: Paddlefish, Blue catfish, Largemouth bass

Best time: Spring and fall for best visibility

Based on community reviews and site data. Conditions vary — always verify before diving.

Best months, historically

What conditions have historically been typical at this site, month by month — not a forecast.

Jan84% 9 kn
Feb84% 10 kn
Mar75% 11 kn
Apr72% 11 kn
May87% 9 kn
Jun98% 8 kn
Jul95% 7 kn
Aug100% 7 kn
Sep97% 7 kn
Oct91% 8 kn
Nov87% 9 kn
Dec83% 10 kn

August hastypically had the largest share of favorable days here. Conditions vary year to year — this is historical context, not a forecast.

Based on 3 years of archive data. Bar height shows the share of days each month whose conditions have historically scored favorably.

Marine life recorded at this site, by month

Recorded observations — evidence of past sightings, not a promise of what you’ll encounter.

Species seen here

PaddlefishCommonly seen
Blue catfishCommonly seen
Largemouth bassCommonly seen
BluegillCommonly seen
Grass carpOccasionally seen
CrappieCommonly seen

Polyodon spathula recorded here Jun–Jul (3 records)
most recent 2012
Ictalurus punctatus recorded here Jun (2 records)
most recent 2012
Lepomis macrochirus recorded here Jun (1 record)
most recent 2012
Micropterus salmoides recorded here Jun (1 record)
most recent 2012

Counts are occurrence records near this site from public biodiversity datasets (GBIF), grouped by calendar month across all sampled years. Sightings vary — past records are context, not a prediction.

Fills & rentals nearby

No dive shops mapped within 25 km. Know one? Add it to the map.

Site details

Mermet Springs is a spring-fed former rock quarry of about 8.5 acres near Belknap in far southern Illinois, and one of the most famous inland dive sites in the country. Its signature attraction is the Boeing 727 used in the film 'U.S. Marshals,' resting with its tail at 15 feet and nose at 50 feet and open for trained divers to swim through, alongside many other sunken vehicles and training platforms. The quarry reaches about 120 feet deep and is run as a full-service commercial dive park.

shorewreck

Deep dark water below the thermocline, overhead environment inside the 727 fuselage (training required), entanglement on attractions, low visibility after heavy rains

Reviews

No reviews yet — this site is waiting for its first. Dived here? Your rating and a few lines help the next diver.

Spot something off?

Help keep this listing accurate for the next diver.