View from highway Looking south at Yellowstone Lake. With a surface area of 136 square miles, Yellowstone Lake is the largest lake at high elevation (i.e., more than 7,000 ft.) in North America. It is a natural lake, situated at 7,733 ft. above sea level. It is roughly 20 miles long and 14 miles wide with 110 miles of shoreline. It is frozen nearly half the year. It freezes in late December or early January and thaws in late May or early June. With half of the earth’s geothermal features, Yellowstone holds the planet’s most diverse and intact collection of geysers, hot springs, mudpots, and fumaroles. Its more than 300 geysers make up two thirds of all those found on earth.