Isa Lake is located in

Yellowstone National Park Yellowstone National Park is an American national park located in the western United States, largely in the northwest corner of Wyoming and extending into Montana and Idaho. It was established by the 42nd U.S. Congress with the Yellowst ...

, in the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its sove ...

Wyoming Wyoming () is a state in the Mountain West subregion of the Western United States. It is bordered by Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho to the west, Utah to the southwest, and Colorado to the s ...

. The lake straddles the continental divide at

Craig Pass Craig Pass (el.), is a mountain pass located on the Continental Divide in Yellowstone National Park in Wyoming. The Grand Loop Road crosses the pass approximately east of Old Faithful Geyser Old Faithful is a cone geyser in Yellowstone Nati ...

Indigenous peoples Indigenous peoples are culturally distinct ethnic groups whose members are directly descended from the earliest known inhabitants of a particular geographic region and, to some extent, maintain the language and culture of those original people ...

have lived in the Yellowstone region for at least 11,000 years. In the 1800s, at the time of the first European exploration of the area, the region was home to several Indigenous Nations including the Nimíipuu,

Absaroke The Crow, whose autonym is Apsáalooke (), also spelled Absaroka, are Native Americans living primarily in southern Montana. Today, the Crow people have a federally recognized tribe, the Crow Tribe of Montana, with an Indian reservation locate ...

, and Shoshone

Nations A nation is a community of people formed on the basis of a combination of shared features such as language, history, ethnicity, culture and/or society. A nation is thus the collective identity of a group of people understood as defined by t ...

Hiram M. Chittenden Hiram Martin Chittenden (October 25, 1858 – October 9, 1917) was an American engineer and historian. A graduate of West Point, he was the Seattle district engineer for the Army Corps of Engineers from 1906 to 1908). Chittenden was one of ...

became the first known European to sight the lake in 1891, while searching for the best routes connecting

Old Faithful Old Faithful is a cone geyser in Yellowstone National Park in Wyoming, United States. It was named in 1870 during the Washburn–Langford–Doane Expedition and was the first geyser in the park to be named. It is a highly predictable geotherm ...

and the

West Thumb Geyser Basin The geothermal areas of Yellowstone include several geyser basins in Yellowstone National Park as well as other geothermal features such as hot springs, mud pots, and fumaroles. The number of thermal features in Yellowstone is estimated at 10, ...

. Chittenden named the lake after Miss Isabel Jelke, from

Cincinnati Cincinnati ( ) is a city in the U.S. state of Ohio and the county seat of Hamilton County. Settled in 1788, the city is located at the northern side of the confluence of the Licking and Ohio rivers, the latter of which marks the state line wit ...

, though it is not clear why. Continental Divide sign at Two-Ocean Lake

Isa Lake is believed to be one of the few natural lakes in the world which drain to two different oceans, another being

Wollaston Lake Wollaston Lake is a lake in north-eastern Saskatchewan, Canada. It is northeast of Prince Albert. With a surface area of (excluding islands; if islands are included), it is the largest bifurcation lake in the world – that is, a lake th ...

. (For similar cases see

List of unusual drainage systems The following is a list of unusual drainage systems. List Bifurcation rivers (active) * The Casiquiare canal – natural waterway connecting the Orinoco and Amazon River, Amazon rivers. * The Chicago River and Calumet River artificially divert wa ...

.) The east side of the lake drains by way of the Lewis River to the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the contin ...

and the west side of the lake drains by way of the

Firehole River The Firehole River is located in northwestern Wyoming, and is one of the two major tributaries of the Madison River. It flows north approximately from its source in Madison Lake on the Continental Divide to join the Gibbon River at Madison Junc ...

to the

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United ...

. 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. The great yellow pond-lily thrives in the lake.

Notes

Lakes of Teton County, Wyoming Lakes of Wyoming Lakes of Yellowstone National Park Great Divide of North America Bifurcation lakes {{wyoming-geo-stub