This is a picture of Isa Lake in Yellowstone National Park. It rests on the continental divide and drains into both the Pacific and Atlantic oceans.
Here is the text form Wikipedia on this lake. I think it is better to quote directly rather than paraphrase:
“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 Miss Isabel Jelke, from Cincinnati, though it is not clear why.
Isa Lake is believed to be the only natural lake in the world which drains to two different oceans. (For similar cases see List of unusual drainage systems.) 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.”
Thanks to Cee Neuner for hosting this challenge. It really gives me a chance to explore the world of black and white photography. You can visit the challenge page here. Go take a peek at her photos and all of those referenced in the comments section.