The bubbles surfacing at Canyon Ferry Reservoir this weekend won't be from a giant sea monster lurking deep down.

Chances are, they're just from Glen McKinnon and his wife, Karen, along with a host of other divers from across the state.

This weekend, more than 100 divers from Billings to Kalispell will gather at Canyon Ferry to explore the lake's attractions and test new gear. The Montana Dive Fest, hosted by the Helena Scuba Club, begins Friday and ends Sunday.

Montana may not seem like a diver's paradise, but the state offers its share of underwater attractions and certified divers.

The interest is enough to support seven dive shops across the state, including the McKinnons' own Helena Scuba, which rents gear, offers certifications, and leads guided trips to underwater worlds.

Few of the lakes around Helena can compare with the clarity of Flathead Lake, which offers visibility up to 40 feet on a good day. But a sunken house boat at Spring Meadow Lake and the original, 110-year submerged dam at Canyon Ferry Reservoir do give divers something to see.

McKinnon, a local instructor, discovered the old dam about three years ago. He was diving near the cliffs on the reservoir's west shore when he swam into something manmade about 110 feet down.

Through repeat dives and research at the Montana Historical Society, McKinnon identified the structure as the old Canyon Ferry Dam, about 1.5 miles upriver from the current dam.

According to the state, the old dam was built in 1896, forming what was known back then as Lake Sewell. The new dam inundated the old dam and buried Lake Sewell, along with much of the river valley.

Evidence of the past is deep down. The top of the old power house sits under 110 feet of water, McKinnon said. The base of the dam is nearly 170 feet down - well beyond the reach of recreational divers.

Ruins include the dam's flood gates and an ore cart with an electric motor still attached. Empty windows, sidewalks and stairs create the illusion of a murky ghost town.

"I take students down to the power house for deep water lessons," McKinnon said. "It's dark. Sometimes you can't see a foot. Sometimes you can see 10 feet. It just depends on the temperature and how the water is moving through there."

Diving in such dark, cold conditions isn't for everyone. McKinnon's wife, Karen, prefers good visibility, though she's not averse to heading down into the lake's dark depths with company.

"If I couldn't touch the bottom, I didn't want to be there," she said, speaking of her prediving days. "The water to me was just kind of scary."

But McKinnon overcame her fears. The Helena diver logged her 200th dive recently off the coast of Honduras. Her log reads like a diplomat's passport - trips to Belize and Grand Cayman, among others.

Canyon Ferry may not offer turquoise blue water and tropic fish. But there's still plenty to see.

"The carp will follow you around," she said. "The trout and walleye tend to be a little skittish. The ling hang out in the rocks. At night, you just see their eyes looking out at you."

Schedule

Friday

2 p.m.: Boat and shore diving

6:30 p.m.: Potluck dinner

7:30 p.m.: Evening and night dives

9 p.m.: Presentation

Saturday

6:30 a.m.: Pancake breakfast

8 a.m.: Boat dives

Noon: Lunch

1 p.m.: Underwater treasure hunt; equipment demos

6:30 p.m.: Catered dinner

7:30 p.m.: Presentation

More info

For more information on Montana Dive Fest, call Helena Scuba at 442-4334, or click here.

Reporter Martin Kidston: 447-4086 or mkidston@helenair.com