National Park Service LogoU.S. Department of the InteriorNational Park ServiceNational Park Service
National Park Service:  U.S. Department of the InteriorNational Park Service Arrowhead
Isle Royale National ParkAerail view of the Rock of Ages Lighthouse on a sunny day.
view map
text size:largestlargernormal
printer friendly
Isle Royale National Park
Nature & Science
Aerial of the northeast side of Isle Royale.

Nature and Science - an Overview

In the northwestern portion of powerful Lake Superior exists a unique and remote island archipelago. Isle Royale National Park preserves 132,018 acres of land-based wilderness that was federally designated on October 20, 1976. The park consists of one large island surrounded by about 400 smaller islands, it encompasses a total area of 850 square miles including submerged land which extends 4 1/2 miles out into the largest fresh water lake in the world. Due to Isle Royale's biological and ecological uniqueness, it was designated an International Biosphere Reserve in 1980. These isolated islands have barely 20 species of mammals compared to over 40 found on the surrounding mainland. Some species have come and gone, often due to the influences of humans. The heavily forested shoreline of Isle Royale appears similar to the mainland’s landscape prior to development. Gulls, ravens, and an occasional eagle or osprey dot the skies; squirrels, toads, mice, and spiders move about the forest floor.


The Ecological Study of Wolves on Isle Royale, now in its 46th year, is the longest running large mammal predator-prey study on earth. Research has shown that all members of the Isle Royale wolf population have descended from a single female, which arrived during the late 1940s. This intense level of inbreeding has led to a 50% loss of genetic variability within the population today. Genetic information suggests that the island’s moose population is most closely related to moose in northwestern Minnesota…perhaps challenging the long-held idea that moose swam across the lake to reach Isle Royale. Did humans bring them here?

A venture by foot, canoe or kayak into the parks interior can transport one back thousands of years into it’s prehistoric past. Around 11,000 years ago, 2 miles of ice lay on top of Isle Royale, pressing it down into the earth and sculpting its topography. The same ice sheet gave birth to powerful Lake Superior as well as hundreds of inland lakes, ponds and bogs. The Greenstone Ridge, which forms the backbone of Isle Royale, is thought by many geologists to be a portion of the largest lava flow on earth.

All in all, Isle Royale is a fascinating ecosystem, responding to influences seen in very few places in all of North America or the world.

Isle RoyaleNational Parkis significant because:

  • It is a remote and primitive wilderness archipelago isolated by the size and power of Lake Superior.
  • Isle Royale is world renowned for its long-term wolf/moose predator/prey study. The park offers outstanding possibilities for research in a remote, relatively simple ecosystem where overt human influences are limited.
  • Park waters contain the most productive native fishery and genetically diverse trout populations in Lake Superior.
A sunset silhouette of a backpacker on a ridge.  

Did You Know?
Although the yearly number of visitors to Isle Royale is less than Yellowstone receives in a day, the Island's per acre backcountry use is the highest of all National Parks in the United States.

Last Updated: July 25, 2006 at 00:22 EST