Did you know? Dozens of shipwrecks litter Lake Union

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SEATTLE — Seattle's Lake Union is known for houseboats, marinas and Gasworks Park, but did you know dozens of shipwrecks litter the bottom of the lake?

People who grew up in the Seattle area may have heard about sunken ships in Lake Washington, but are not aware of shipwrecks under the waves of Lake Union.

PHOTOS: Secret shipwrecks of Lake Union

A group of marine experts have been diving and documenting all of the sunken vessels so the public can get a glimpse of the mysteries on the lake bottom.

Only 20 feet down, through the milfoil and murkiness of Lake Union, divers from the Maritime Documentation Society have swam back in time to discover dozens of ships that have been deteriorating on the lake floor for decades.

"There's wrecks on top of wrecks. It's like a landfill basically with water over the top,” said diver Erik Foreman.

Seven or eight years ago, the Center for Wooden Boats partnered with marine electronics experts, Edmonds-based Ross Laboratories, to perform sidescan imagery of Lake Union.

They charted and mapped the discoveries, then sent Foreman and Chris Borgen into the water.

"It was just amazing to see –‘Oh, my gosh, all this stuff is in just 35 feet of water,’” said Borgen.

Among the most historically significant discoveries was an old wooden mine sweeper, built in 1941 and used during the War to clear a path for destroyers in the Pacific.

After it was turned into a fish processing boat, it sank at its mooring on Lake Union, and took some of the dock down with it.

"This lake was a huge industrial spot.  They used to do all sorts of ship fitting here.  They'd break ships up, cut them up, sink the parts, you know.  They didn't want to get rid of them.  So they'd just dump them right in the lake,” said Borgen.

The divers are documenting every wreck they find, whether they're identifiable or not, because they want people to know more about the marine history of the Pacific Northwest.

"It's cool to be able to show them what the city was like a hundred years ago, the kind of industry, the vessels, and everything else that was around this area,” said Borgen.

The people working on the project are hoping to eventually have detailed maps and interactive information so people know where the wrecks are.

But it's illegal to dive in Lake Union without permission from Harbor Patrol and the Department of Natural Resources, so they're being a little cautious about releasing specific details about the wrecks.