Isa Lake

Isa Lake is a small alpine lake in Yellowstone National Park, Wyoming, notable for sitting on the Continental Divide. It is widely known for having outlets that flow toward both the Atlantic and Pacific drainage basins.

The main attraction is the lake’s unusual hydrology rather than large size; a short roadside pullout and footpath provide easy viewing from the Grand Loop Road. The site is commonly visited en route between the Old Faithful area and the West Thumb/Grant Village area of the park.

The lake was named and mapped during early park surveys and has appeared on visitor maps since Yellowstone’s establishment as a national park. Its status as a curiosity on the Continental Divide has made it a traditional stop for park visitors.

Isa Lake lies inside Yellowstone National Park on the Continental Divide, along the Grand Loop Road in the park’s southwestern section of Wyoming. The site is reachable from the main park road system and is a brief stop on routes connecting major attraction areas.

• Bifurcated drainage: The lake sits directly on the Continental Divide and is one of the few in North America that drains to two different ocean basins.