The Hunt for the Great Freshwater Whale: Welcome to one of only a few places in the world where divers can encounter paddlefish in clear water.

Mission accomplished. Still photos taken from the author's video of paddlefish in Mermet Springs show the massive fish backlit by the sun.

Video camera at the ready, I moved through the green water of Mermet Springs, closing in on my quarry, the biological oddity known as Polyodon spathula, commonly referred to as the paddlefish or spoonbill. One of the largest freshwater fish in the U.S., paddlefish can easily weigh 95 pounds and are sometimes referred to as freshwater whales.

These bizarre-looking fish are filter feeders and inhabit large, muddy rivers, such as the Missouri, Mississippi and Ohio, but the odds of a diver ever finding one in those turbid conditions, much less getting a clear shot, are slim. In fact, Mermet Springs is one of only a few places in the world where divers can encounter and photograph paddlefish in a relatively clear environment.

A spring-fed rock quarry, 120 feet deep, and covering about 8.5 acres, Mermet Springs is a first-class dive facility in southern Illinois. It's home to a variety of fishes, including albino catfish, perch, crappie, bass and another aquatic dinosaur--the sturgeon. While the paddlefish skims plankton from the water column, sturgeon have a rubbery, siphon-like mouth that acts like a vacuum cleaner to suck food off the bottom. Both of these bizarre species were caught in nearby rivers and released into the spring, where they have since flourished.

There's more to Mermet Springs than just fish. One of the most popular underwater attractions is a Boeing 727 passenger jet used in the movie U.S. Marshals. There is also a school bus, semitrailer truck, cabin cruiser and two Cessnas sunk in the quarry for divers to explore.

The amenities at Mermet Springs include shower and changing rooms, covered pavilions with picnic tables, gear racks, scenic campsites, picnic areas, access ramps and a chairlift for handicapped divers. There's also a swim beach and four docks with custom-built stairs for easy entries and exits.

Designed in part to be a scuba training facility, Mermet Springs has classrooms, an anchored boat for practicing boat diving skills and six underwater training platforms.

Designed in part to be a scuba training facility, Mermet Springs provides easy access for divers.

Dive In: Mermet Springs

Location

Mermet Springs is located in Illinois on U.S. Hwy. 45 between Metropolis and Vienna. The quarry is open six days a week from April through November, and five days a week from December through March. The facility is closed in January. Fishing is prohibited.

The Rules

There is a $15 entrance fee for divers, $5 for nondivers, and camping is $5 per person per night. All visitors are required to register upon entering the grounds. Divers must present valid C-cards, or be accompanied by an instructor.

Water Conditions

Temperatures range from the low 40Fs at depth during winter to the mid-80Fs above the thermocline in late summer. During winter, or for year-round deep diving, a dry suit or 7mm wetsuit is recommended. In summer, a 3mm wetsuit is adequate for diving above the thermocline. Visibility ranges from 15 feet to
more than 60 feet, depending on rainfall and other environmental conditions. Current temperatures and water conditions are posted at www.mermetsprings.com.

Dive Profile

The quarry reaches a maximum depth of 120 feet and the underwater terrain ranges from the shallows of the sloping swim beach to the depths of sheer rock walls.

Dive Operator

The on-site dive shop offers a full range of rental gear, air fills and nitrox. For information, call the dive shop at (618) 527-DIVE, web: www.mermetsprings.com.