At least 75 species of birds, eight species of mammals, two species of snakes and four species of amphibians have been observed using these islands and the surrounding waters. Large colonies of herring gulls can be found nesting on Cattle Island, McIntyre Island and Gull Rock. The red breasted nuthatch, cedar waxwing, red-eyed vireo and several species of warbler are readily seen on Lighthouse Island. Common loons, common mergansers and red-breasted mergansers are commonly seen off-shore.

Whether photographing wildlife from a boat or pursuing your target on Lighthouse Island, visitors are offered a wide variety of options. Birds, reptiles, amphibians and mammals can all be found on the island. The historic stone lighthouse, the grays and pinks of the exposed bedrock, the blues of the lake and the contrasting greens of the trees offer photographers beautiful landscape shots. The bedrock itself offers shutterbugs a chance to capture the unique patterns caused by rocks and boulders cutting grooves into the rock (glacial striations) as glaciers moved slowly over the landscape. A wide variety of trees, lichens and wildflowers grow on the island providing photographers a variety of subject matter.

Harbor National Wildlife Refuge has one hiking trail which extends from the dock on Lighthouse Island to the lighthouse and then to opposite side of the island near the old Fog Signal building.  This beautiful trail passes within yards of a bald eagle's nest and past several species of wildflowers including twinflower, smooth Solomon's seal, bluebead, columbine, Canada mayflower, and honeysuckle vines.  There are several places to stop and enjoy the spectacular views.