Nordyke Island is about 35 feet (11 m) high, flat, and grass-topped, located in Kamishak Bay about 115 miles (186 km) northwest of Kodiak and 96 miles (155 km) southwest of Homer, Alaska. Two smaller flat grass-topped islands are southwest of Nordyke Island, and a series of reefs and rock ledges are exposed at low tide between Nordyke Island and McNeil Head on the southern shore of Kamishak Bay.
Kamishak Bay is a broad indentation at the northern end of the Alaska Peninsula, about 20 miles (32 km) northwest of Cape Douglas near the mouth of Cook Inlet. Kamishak Bay has numerous reefs rising to within a few feet of the surface scattered throughout the area. During strong northwest to west winds, that are common after mid-August, the bay experiences stronger winds due to the funnel effect of the mountains in the Aleutian Range to the west. These winds are often accompanied by a short, high, choppy sea on flooding currents and the area is a known hazard for small vessels. Kamishak Bay is shallow and larger vessels generally stay within charted channels, although there is a good anchorage in the lee of Nordyke Island.
The area surrounding Nordyke Island and the southern shore of Kamishak Bay is underlain by sedimentary rocks of Upper Jurassic age (about 161 to 146 million years ago). These rocks amount to at least 6,000 feet (1829 m) in total thickness and represent the Chisik conglomerate and the Naknek formation. These rocks are exposed at low tides as wave-cut platforms that extend up to 2 miles (3.2 km) from shore. Read more here and here. Explore more of Nordyke Island here: