Isa Lake

Isa Lake
Location	Yellowstone National Park, Teton County, Wyoming, US
Coordinates	44°26′27″N 110°43′09″W
Type	Natural lake
Basin countries	United States
Surface elevation	8,297 feet (2,529 m)

Isa Lake is located in Yellowstone National Park, in the U.S. state of Wyoming. The lake straddles the continental divide at Craig Pass and was first discovered in 1891 by Hiram M. Chittenden, who was exploring the best routes for a road to connect Old Faithful and West Thumb geyser basins. Chittenden named the lake after Isabel Jelke, a woman from Cincinnati, though it is not clear why.

Map of Continental Divide at Isa Lake

Isa Lake is believed to be the only natural lake in the world which drains to two different oceans backwards. (The man-made Gatun Lake in Panama also drains backwards into the Atlantic and Pacific Oceans via the Panama Canal.) The east side of the lake drains by way of the Lewis River to the Pacific Ocean and the west side of the lake drains by way of the Firehole River to the Atlantic Ocean. This is the opposite of what one would expect since the Atlantic Ocean is east of the lake and the Pacific Ocean is to the west.

The lake is easy to visit as it is adjacent to the road that now connects the Old Faithful and West Thumb geysers basins, on what is known as the "lower loop" of the figure-eight roadway which traverses through Yellowstone.

Images of Isa Lake

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  Isa Lake, 1921
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  Isa Lake on Craig Pass Road
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  Isa Lake