COEUR d'ALENE - At 90,000 acres, Lake Pend Oreille is the largest body of water in Idaho.

Because of its size and extreme depth - it can easily hide Navy submarines - the lake has over the years inspired numerous legends and myths, almost all of which are entirely false.

False, but fun.

A huge, Nessie-like sea monster that occasionally comes ravening from the depths, for example. An eternal layering of ice at the bottom of the lake, never to melt. The water being so cold that dead fish don't rot; their preserved corpses just pile up forever.

The list goes on.

"I had somebody just the past year tell me the lake is bottomless," said Melo Maiolie, Idaho Fish and Game regional fishery biologist. "It's not bottomless."

A bottomless lake, he added, would probably not be very good at holding water.

Maiolie knows Lake Pend Oreille, particularly its darkest, most enigmatic places, better than most. He led a team of IDFG biologists on a deep-water mission in the summer of 2008. Their findings were analyzed that year and in 2009.

He shared the story Tuesday morning at the Lake City Senior Center in Coeur d'Alene, where local fishermen, hunters and IDFG officials gathered for the February Sportsmen's Breakfast.

The mission had no defined goal, Maiolie said. It was an exploratory outing - the biologists simply wanted to know what, if anything, was living in the deep.

"Pend Oreille has always been something of a mystery," Maiolie said.

Traversing the main body of the lake, keeping clear of Navy operations near the western shore, Fish and Game personnel used an echo-sounder to probe depths more than 1,100 feet. Every second the machine would emit a ping, which would travel to the bottom and echo back to the boat.

Much like a standard fish finder, the echo-sounder and its bouncing pings revealed underwater objects, both alive and inorganic. On the graph they registered as vague forms or lines.

At one point, a crescent-shaped form appeared in very deep water, suggesting a fish about 12 inches long.

"There were fish out there," Maiolie said. "And we could get a pretty good size estimate from them."

One-thousand feet below the surface is inhospitable territory, the biologist explained. At that depth nothing grows, not even algae, because without sunlight there can be no photosynthesis. The water is always cold, usually about 40 degrees, and pitch-black. The pressure is so intense - 441 pounds per square inch - it can crush a fish's swim bladder.

IDFG was curious: What could possibly be living in that abyss?

To find out, Maiolie and his colleagues deployed 150-foot weighted gillnets, with minnow traps attached to the sides. Once the net was released, it took 25 minutes to reach the bottom.

The fish were few and far between. IDFG estimated the fish density below 1,000 feet at .07 fish per acre, or about 1,200 fish altogether.

Nonetheless, the crew hauled up three bull trout, two pygmy whitefish and one slimy sculpin - an odd little critter with a big head and bulging eyes.

"It's interesting that all three were native species," Maiolie said. "Somehow over the last 10,000 years, the native fish have colonized the bottom of the lake."

The bull trout were whiter than normal and difficult to identify, Maiolie said. They measured a respective 10, 11 and 21 inches. One of the pygmy whitefish was aged at 14 years old, and was quite possibly the oldest whitefish ever found.

IDFG kept the slimy sculpin in an aquarium, and it lived for several months.

"(Maiolie) did a real good job," said Quentin Weller of Hayden, who attended the Sportsmen's Breakfast. "Put on a good presentation. That was real interesting about the depth and everything."

Will Cline of Coeur d'Alene is a longtime volunteer with Idaho Fish and Game. He used to fish Lake Pend Oreille, but doesn't hit the water too much anymore.

"I think it was great," Cline said. "This is the first time I've ever heard (Maiolie) give a presentation. Obviously he's pretty well-acquainted with Pend Oreille."

Some of the lake's far-fetched legends could be rooted in Native American folklore, Cline offered.

"Indians have gotten into that, too, I would imagine," he said. "They were here before we came around. They probably didn't have all this fancy equipment, though."

Putting that equipment to good use, Maiolie and others challenged the rumors and myths, and found no sea monsters. They did, however, shed some scientific light on the darkest depths of Lake Pend Oreille.