Parting of the Waters

https://commons.wikimedia.org/wiki/File:Two_Ocean_Pass_USGS_Topo.png

In Wyoming’s Teton Wilderness, North Two Ocean Creek splits into two smaller creeks: Pacific Creek flows westward to the Pacific Ocean, Atlantic Creek eastward to the Atlantic.

In principle this makes it possible for a fish to swim upstream from the Pacific, cross the Great Divide, and pass down into the Atlantic. This may be how the Yellowstone cutthroat trout came to be found in both the Snake and Yellowstone rivers.