Thumb Cove State Marine Park is located approximately nine miles south of Seward on the east side of Resurrection Bay. The park's 720 acres include the southeast shoreline of the cove; a long beach of fine to medium sand and beach cobble; forested uplands of spruce, hemlock and alder; and most of the waters of Thumb Cove. Perhaps the most striking geologic feature in the area is Porcupine Glacier, towering above the park and providing a dramatic backdrop to this popular marine destination.

Thumb Cove SMP is a favorite stop for Seward's recreational boaters and camping is popular along the beaches. Fishing for salmon is a favorite activity during the various runs, and Thumb Cove offers good protection from the often unstable weather of Resurrection Bay. Fresh water is available from a stream flowing from Porcupine Glacier. Thumb Cove SMP has two Public-Use Cabins for rent. One of these is wheelchair accessible. Two mooring buoys are located within the park; one in front of each Public-Use Cabin.