Visitor information guide to Lake Desmet boat rentals and jet ski rental company at this deep-blue body of water up in Johnson County, Wyoming. Named after the first white man to lay eyes on it back in 1840, Lake De Smet is a huge, deep watery wonder of the state. It catches the eye, all the sudden, off to the east from Interstate 25. Lake DeSmet is a stunner, in a breathtaking setting, just a strong stone's throw from the base of the Bighorn Mountains, and smack dab in a place with a wonderfully-long history. Today's huge lake to enjoy fishing, water sports, waverunners, watercraft, boat tours and a long tradition that lives on with our services.