Diving into mysterious Crater Lake

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Scientists believe that after the volcanic hole left in Oregon's Cascade Range cooled off, it filled up with snowmelt and rainwater during the next 600 to 800 years to form Crater Lake. Because the volcanic terrain limits the amount of nutrients in the lake, and prevents streams coming in or out of it, the water is pure blue and largely comprised of snowmelt.

The volcano erupted again nearly 4,000 years ago to form volcanic structures within the lake--the largest of which is Wizard Island.

Wizard Island is the focus of much of today's field studies, because the scientists have found thick concentrations of moss hanging like icicles from the island's steep edges. The team is also trying to understand the many large pits within the old moss beds, which when examined show layers of green and white algae, with live cells growing at the tips of the moss.

"At this point, it's all a mystery," Collier said.

In 1988 and 1989, a team of researchers sent the first human-driven submarines into the lake. Now, the team of scientists is using one of the most powerful remotely controlled robots, as well as high-resolution sonar beams to collect data and construct a map of the ecosystem under the lake's surface.

"With the crazy depths of this stuff, this kind of technology is the only way we can get to it," said Mark Buktenica, an aquatic scientist and lead researcher. Buktenica was referring to the limits of scuba diving in the lake--divers can typically only go as far as 100 feet deep before getting sick due to the altitude.

On Tuesday, the scientists were exploring an area of the lake called Danger Bay with a remotely operated vehicle, or ROV robot, which is capable of diving 1,500 feet. (The ROVs are typically used as rescue vehicles.) The moss beds start at depths of 85 feet and go down as far as 600 feet.

The ROV robot is equipped with two high-definition digital cameras, one that takes color video and another for black and white, as well as GPS for navigation. Sonar on the top of the robot also collects data on the biomass of the moss, blue-green algae, and other life in the lake.

It has seven thrusters--four mechanisms to go forward and reverse, two to go side to side, and one to spin. The device is also neutrally buoyant, meaning that it doesn't sink or float. It's controlled by an altimeter, which measures depth and can be set to stay a certain distance from the lake floor or wall.

Two engineers on a boat control the robot's movements. And data and video from the robot is transmitted via wire to a computer on the deck of the boat. The PC takes in and transmits signals from the altimeter.

Early assumptions about the moss are that it is nearly 6,000 years old, or as old as the lake itself. But dating the moss is tricky, given that carbon-dating techniques don't work on the almost nutrient-free environment of the lake. Instead, the scientists are attempting to date the pollen that blows into the lake and gets embedded in the sediment.

On Tuesday, the views of Crater Lake were slightly veiled by ash and smoke from a wildfire in the forests around the lake. Brian Kahn, a park ranger with the National Park Service, said that the fire started July 23 after a dramatic storm sent temperatures from 90 degrees to 60 degrees within an hour, and lightning torched parts of the forest. The storm was so fierce that tourists were trapped on Wizard Island.

But a nearby fire isn't going to dampen the enthusiasm of the lake researchers about the local environment.

"We're talking about hundreds of thousands of years of geology exposed," Collier said.