Dive Site Guide · Belknap, Illinois
Mermet Springs
Mermet Springs is a purpose built dive park that consistently delivers clear procedures, reliable fills, and organized shore facilities. It is the most complete quarry option within a day’s drive of Chicago for training, practice, and deep profiles. Use the notes below to navigate check in, fills, thermoclines, and where to stage gear efficiently.
Site Snapshot
- Type
- Purpose built dive park
- Hours
- Generally 9 am to 6 pm or 10 pm, depending on the day
- Night diving
- Allowed
- Temperature
- Around 40 ft, expect near 50 F or less; very cold below about 60 ft
- Fills
- Staff track fills on a whiteboard; settle up at the end of the day or weekend
- Nitrox
- Partial pressure blended; O2-clean tanks required; custom blends on request
- Staging
- Covered gazebos, picnic tables, whiteboards, and hanging bars
- Training
- Platforms installed down to 100 ft
- Lighting
- Dark below about 40 ft; bring a primary light
- Shallows
- The 0–20 ft band can be murky during classes
- Navigation
- Major attractions and platforms connected by marked lines and signs
- Plan Your Visit
Things to Know
- Best overall dive location in the Chicagoland regional area.
- Generally open from 9 am to 6 pm or 10 pm depending on the day (night dives are allowed).
- Significant, visible thermoclines. Around 40 ft expect a drop near 50 F or less. Very cold on the deep side below about 60 ft.
- Large, well managed fill station with Nitrox blending. Drop tanks, give your name, and staff track fills on a whiteboard. You settle up at the end of the day or weekend.
- Nitrox is partial pressure blended, not banked. Tanks must be O2 clean for Nitrox fills. Custom blends are available on request.
- Excellent suit up area with covered gazebos, individual picnic tables, mounted whiteboards, and bars for hanging exposure gear and rigs.
- Very large catfish patrol the quarry and are not shy.
Diving Activities
- Strong training infrastructure supported by the gazebos and platforms.
- Large water area supports technical training and DPV dives.
- It gets dark below about 40 ft; bring a primary light.
- The 0 to 20 ft band can be murky during classes; maintain solid buddy awareness.
- Training platforms are installed down to 100 ft, making it ideal for deep practice.
- Dock entries have only small in water staging space, so conduct briefings on land or while floating.
How to Check In
- Fill out the liability release form online before you arrive.
- Pull through the gate and cross the railroad tracks.
- Park in the first lot unless directed otherwise by staff.
- Go to the office, check in, pay the entry fee, and present your certification card.
- Go to your assigned diver gazebo. Groups can request a gazebo in advance.
- Suit up and dive.
Dive Map
Dive Map as of Aug 2024
- Surface swim to the plane, descend, and you can tour most attractions on a single AL80 if you plan conservatively.
- Major items and platforms are connected with well marked lines and signs underwater.