Aniakchak National Monument and Preserve

A river ribbons through the landscape at the Aniakchak preserve.

The craters of the volcanically active Aleutian Mountains.

The caldera wall along Surprise Lake in the Aniakchak park.

Aniakchak is a six-mile-wide, 2,000-foot-deep caldera formed by the collapse of a 7,000-foot volcanic mountain.

The caldera's Surprise Lake, heated by hot springs, cascades through a 1,500-foot rift in the crater wall.

West of the caldera is the waterfowl and migratory bird habitat of Bristol Bay's coastal plain. To the east, rugged bays and inlets of the Pacific coast and offshore islands provide habitat for sea mammals and sea birds.

Sockeye salmon spawn in Surprise Lake and the Aniakchak River.

The park lies 450 miles south of Anchorage on the roadless Alaska Peninsula. The weather can be severe during all seasons. Few people visit, but those who do are rewarded by wildlife and geological wonders.

Hikers find excellent hiking conditions atop the ash and cinder fields of the caldera floor, but they also face swift, cold rivers, patches of dense vegetation and brown bears.

A few parties of intrepid rafters run the challenging Aniakchak River each year, mostly in July. In three or four days, you can float from Surprise Lake, past treeless tundra, to the ocean. A hefty budget and pre-tested skills and gear are essential.

Air charters fly from King Salmon to several points in the preserve. While backcountry permits are not required, it is highly recommended that visitors file an itinerary with the National Park Service and do not travel alone. The park has no marked trails, campgrounds or services.

Hunting is allowed in the preserve area of the park.