Isa Lake is one of the strangest little lakes in the world. Perched right on the Continental Divide at Craig Pass in Yellowstone National Park, this lily-covered pond drains to two different oceans at once — and, oddly, does it backwards. It’s tiny, but it’s a genuine natural curiosity worth knowing about. This guide is part of our growing Wyoming Lakes Database.
Isa Lake at a glance
- Location: Craig Pass, on the Continental Divide, Yellowstone National Park (Teton County, WY)
- Elevation: about 8,262 ft
- Claim to fame: drains to both the Pacific and the Atlantic/Gulf — one of the very few lakes on Earth that does
- Character: a small, shallow pond covered in yellow pond-lilies
- Named: by engineer Hiram Chittenden in 1891, for Isabel Jelke of Cincinnati
The lake that drains to two oceans
Isa Lake sits exactly astride the Continental Divide, so its two ends spill toward opposite sides of the continent. The east end flows via the Lewis River toward the Pacific, while the west end drains through the Firehole River toward the Gulf of Mexico and the Atlantic. Stranger still, because of the way the divide crosses it, each side effectively drains “the wrong way” — a quirk that delights map-lovers and Yellowstone guides alike.
A pretty pond on Craig Pass
For all its fame, Isa Lake is small and quiet, its surface thick with the great yellow pond-lily in summer. It was first recorded in 1891 by engineer Hiram Chittenden while he scouted the road between Old Faithful and West Thumb, and he named it after Isabel Jelke. Today that same road runs right past it, making Isa Lake an easy — if easily missed — stop on Yellowstone’s lower loop.
Know before you go
- It’s in Yellowstone: right on the road at Craig Pass between Old Faithful and West Thumb — a quick roadside curiosity.
- Not a fishing lake: a tiny, lily-filled pond — come for the story and the view, not to cast a line.
- Best in summer, when the pond-lilies bloom and the pass is open.
Frequently asked questions
Why is Isa Lake famous?
It sits on the Continental Divide and drains to two oceans at once — the Pacific and the Atlantic/Gulf — and it does so “backwards,” making it one of the most unusual little lakes in the world.
Where is Isa Lake?
On Craig Pass, on the Continental Divide in Yellowstone National Park, right beside the road between Old Faithful and West Thumb.
Can you fish Isa Lake?
Not really — it’s a tiny, shallow, lily-covered pond valued as a natural curiosity, not a fishing lake.
Related: explore more small lakes of Wyoming, or head back to the Wyoming Lakes Database.
Explore more Wyoming lakes: the largest lakes in Wyoming and the deepest lakes in Wyoming.
