This legendary waterway flows right through Island Park, drawing fly fishers from across the country who come specifically for its wild rainbow trout population. Trails That Test Your LimitsLace up your boots tight because the trail system around Island Park does not ease you in gently. It stretches across a wide range of terrain, offering hikers a chance to move through meadows, forests, and open ridges with sweeping views of the Henrys Lake Mountains. Henrys Lake, A Hidden TrophyJust a short drive through the plateau brings you to Henrys Lake, a high-elevation body of water that sits at around 6,472 feet. Planning Your Visit RightTiming matters when you plan a trip to Island Park.