Some of the same natural forces that once made Yellowstone National Park so scenic also made Island Park similarly beautiful. Island Park sits in the world's largest caldera, 23 miles in diameter, created from a volcano that collapsed in prehistoric times. Now covered in a dense forest of pine and wildflowers, it is popular for hiking and fishing in the summer and cross country skiing and snowmobiling in the winter. The Henry's Fork of the Snake River is world famous for fly fishing, and is curtailed here to form the 7,000 acre Island Park reservoir, popular to both anglers and boaters. The Henry's Fork then winds through the meadows of one of Idaho's most premiere state parks, Harriman State Park, also known as the Railroad Ranch.
Island Park is a rustic area with many ranches and guest lodges where you can fully experience the atmosphere of the region. A most rewarding side trip in route to Island Park is the Mesa Falls Scenic Byway. Mesa Falls is 65' high and can be viewed from an observation point high above the falls. Upper Mesa Falls is 112' and has a network of viewing platforms, as well
as a visitors center.
Just before the Montana border, you will find Henrys Lake and Henrys Lake State Park. Located only 15 miles west of Yellowstone National Park, this high mountain lake is the kind of place fisherman dream about. The state park is open in summer and fall for anglers to fish for cutthroat, brook and rainbow-cutthroat hybrid trout. Another source for the Henry's Fork comes from Big Springs, where 120 million gallons of water bubble up into the water each day. The Big Spring Nature Trail, six miles north of the Island Park Ranger Station, is a half-mile, handicap-accessible trail that provides great viewing of osprey, bald eagles, waterfowl and an occassional moose, deer or muscrat.