Bear Lake is beautiful, freshwater lake that runs 20 miles along the border between Idaho and Utah. It is close to the Cache National Forest and Minnetonka Cave as well as the National Oregon Trail Center in Montpelier, Idaho.

This bright blue lake, with its tight swirl of a light-toned sediment, caught the eye of an astronaut on the International Space Station. Situated on the Idaho-Utah border, Bear Lake is one of the bigger lakes in the Rocky Mountains.

The two swirls near the center of the 30 kilometer (19 mile) long lake are rotating in the deepest water—perhaps from outflow from Swan Creek or Fish Haven Creek. North Eden Creek has laid down a little delta at its mouth. Two center-pivot irrigation fields sit on the delta, one of the few flat places in this mountainous landscape.

The more diffuse swirls at the north end of the lake (lower right) likely formed from sediment entering from North Eden Creek. This sediment is carried north along the shoreline by lake currents, joining with sediment eroded from the white beaches.

When the north-end beach formed, it cut off of Bear Lake from the Mud Lake lagoon. Muddy sediments subsequently collected to form a dark-toned, vegetated wetland now protected as the Bear Lake National Wildlife Refuge. A much larger protected area is the Cache National Forest, visible across the entire top part of the image. Dramatic canyons like Fish Haven Canyon cut deeply into the Wasatch Mountains.

—

Credit: NASA