Oldmans Bay is about 3 miles (4.8 km) across, located on the southwestern coast of Kalgin Island in Cook Inlet, 55 miles (89 km) northwest of Homer and 30 miles (48 km) west-southwest of Kenai, Alaska. The local name was first reported in 1958 by the U.S. Geological Survey. Kalgin Island is about 13 miles (21 km) long and located on the west side of Lower Cook Inlet. The name is from the Tanaina and first reported in 1840 by the Russian scientist I.G. Wosnesenski. The name “Isla del Peligro”, meaning “danger island”, was published on charts by Galiano in 1802.

The Kalgin Island Critical Habitat Area is adjacent to Oldmans Bay and consists of a flat green expanse of wetlands surrounding Swamp Creek on the southeast shore of Kalgin Island. Swamp Creek flows northeast for about 3 miles (4.8 km) to Cook Inlet. The critical habitat area provides spring and fall resting and feeding habitat for swans, geese, ducks, and shorebirds and is an important alternative habitat used each year by a portion of the thousands of waterfowl that use nearby Redoubt Bay wetlands.

Oldmans Bay is mostly an exposed mudflat at low tides supporting a moderately rich biota of invertebrates such as clams and worms. Large boulders scattered on the mudflat are glacial erratics and provide a hard stable habitat for rockweed, periwinkles, whelks, and barnacles. Despite the harsh conditions of Lower Cook Inlet, these plants and animals survive major disturbances by wave action, currents, and seasonal ice scour. Read more here and here. Explore more of Oldmans Bay here: