The existence of a large body of water in an arid region, especially a salt lake, attracted early attention. Native American cultures used the freshwater marshes and streams around the lake for hunting and fishing. The first European reports of the lake seem to have been by Baron Lahontan, who reported in 1703 that he had seen a region west of the Mississippi which contained a large salt lake. The next recorded information about the lake came from the Dominguez-Escalante expedition. Reaching Utah Lake in 1776, they were informed by Indians that it was joined to a much larger lake to the north whose waters were "harmful or extremely salty wherefore . . . anybody getting a part of his body wet instantly feels severe itching around the wet part." The most important effect of the Dominguez-Escalante report was its inclusion of a map showing a river connecting the Great Salt Lake to the Pacific Ocean. This mythical river was later sought by explorers and settlers as a route to the Pacific.
Trappers explored the region of the Great Salt Lake, beginning with Robert Stewart, who was at Bear Lake in 1812 but apparently did not visit the salt lake. Later trappers visited the lake, but is unclear who was first. Jim Bridger reportedly saw the lake in 1824. In 1826 a group of four trappers from the Rocky Mountain Fur Company spent twenty-four days circumnavigating the lake, seemingly putting to rest the idea of a river flowing from it to the Pacific Ocean. In spite of this, the Frémont expedition of 1843-44 visited the Great Salt Lake in 1843 and searched for a river flowing west to the Pacific, finally concluding that the lake indeed occupied part of a great basin which had no drainage to the sea.