Map of Yellowstone showing major rivers and continental divide

Map of Yellowstone National Park showing the major rivers and the continental divide (red dashed). Yellowstone Caldera is oulined by purple dashed line. Water flowing south and west of the divide ends up in the Pacific Ocean, whereas water north and east of the divide ends up in the Gulf of Mexico. Isa Lake is located on the continental divide, and water from the lake flows to both the Gulf of Mexico and the Pacific Ocean.