Despite its proximity to the mainland of Whatcom County, Chuckanut Island supports vegetation more closely resembling that of the San Juan Islands. Douglas fir (some well over 250 years old), grand fir, madrone and western red cedar form the forest canopy of this flat-topped, five-acre island. The understory is dominated by salal, ocean spray and snowberry.

Sculpted sandstone walls rise above an intertidal area rich in marine life that rings the island. Barnacles, snails, rock crabs, sea cucumbers, limpets, hermit crabs and blue mud shrimp are just a few of the 55 marine invertebrate species found here. As scientists continue to study the island's intertidal habitats, the list of marine invertebrates continues to grow.

Surfbirds, which winter in flocks of two dozen or more in Chuckanut Bay, frequently perch on the island's rocky shore. In flight, they share the sky with two bald eagles that nest on the island.

Because there is no source of fresh water on the island, human impact has been slight. A small opening in the forest is all that remains to remind visitors that people once attempted to eke out a living on this out-of-the-way isle.

Frances Gates McCord and Cyrus Kingsley Gates donated this haven in Chuckanut Bay to The Nature Conservancy of Washington in 1976, naming it after their father, Cyrus Gates. Today, the residents of nearby Chuckanut Drive are strongly protective of the Cyrus Gates Memorial Preserve and the mainland shores as well. The island's volunteer steward frequently travels by motorboat to care for the island, keeping a constant watch for campfires and campers, neither of which is allowed.