Castle Cape extends about 10 miles (16 km) northeast from the Alaska Peninsula and forms the southern entrance to Chignik Bay, separating Castle Bay to the northwest from the Pacific Ocean to the southeast, about 45 miles (72 km) northeast of Perryville and 9.5 miles (15 km) southeast of Chignik, Alaska. The point at the end of the cape is formally called Tuliumnit Point but is locally called Castle Cape according to the U.S. Geological Survey in 1911. This cape was first described in 1898 by Lieutenant Commander Jefferson F. Moser of the U.S. Navy from the U.S. Bureau of Fisheries steamer Albatross. Castle Cape is over 1200 feet (366 m) in elevation and the distinctive turreted summit formation and pronounced stratified rock exhibiting a pattern of contrasting dark and light layers serves as a well-known navigational landmark for passing ships. The deep embayments extending southwest from the cape are called the Castle Cape Fjords and consist of extremely rugged mountains deeply incised by the sea. These rocks are part of the Peninsular terrane, the structural geological unit that encompasses much of the Alaska Peninsula. The Peninsular terrane is a Triassic to Jurassic island-arc complex that was accreted to the North American plate by the Early Cretaceous on the geological time scale. The terrane is comprised of the Iliamna and Chignik rock formations. The Late Cretaceous Chignik formation is exposed on the south side of Chignik Bay between Chignik Lagoon and Castle Cape. The Chignik Formation is a cyclic sequence of rocks representing predominately shallow marine to nearshore marine environments in the lower part, and predominately continental environments in the upper part of the section. The formation consists of sandstones, shales, and conglomerates, with some thin beds of coal. The thickness of the formation in the Chignik Bay region is at least 1,968 feet (600 m). The sedimentary rocks were dated from both plant and shell fossils of the Late Cretaceous. Sandstone from the Chignik formation north of Castle Cape has also yielded dinosaur tracks of a hadrosaur.

Archaeological sites approximately 100 miles (161 km) northeast of the Chignik region indicate that humans have inhabited the northeast Alaska Peninsula for a minimum of 9,000 years. In addition, sites located about 50 miles (80 km) northeast of Chignik indicate a series of human occupations from 2000 to 300 years ago, and sites 60 to 200 miles (97-322 km) southwest of the Chignik region indicate that human occupants were present over the past 5,000-6,000 years. Most historical and prehistorical occupation sites in the Chignik region are located on or near productive salmon streams where stone tools have been found including notched net sinkers that indicate a continued reliance on fishing, most likely for salmon. The earliest recorded visit by western explorers to the Pacific Coast of the Alaska Peninsula occurred in 1741 with Vitus Bering‘s expedition in search of unoccupied areas and resources for Russian exploitation. A second expedition in the 1760s brought an influx of Russian fur traders to the Alaska Peninsula who succeeded in gaining control over Indigenous inhabitants. Early Russian explorers encountered Aleut Unangan speakers from the west and southwest Alaska Peninsula and Yup’ik speakers who were ancestors to the Sugpiat Alutiiq people from the central and eastern Alaska Peninsula. Archaeologists and linguists believe that the cultural borderline that separated the Unangan Aleut people to the west and the Sugpiat Alutiiq people to the east was near the Chignik region. The Alutiiq people were maritime hunters whose homeland was the southern Alaska Peninsula as well as Kodiak Island, lower Cook Inlet, and Prince William Sound. The sea, as well as inland streams and tundra, provided them with food, oil, and raw materials to manufacture clothing, shelters, and boats. They were extremely skilled at hunting and adept at using seal skin kayaks or bidarkas and larger open boats. The hunting skills of Alaska Natives made them a target for Russian exploitation and most males were forced to labor. Russians introduced European goods, trade for cash, Christianity, and intermarriage, as well as new diseases of which Alaska Natives had no immunity. Massive deaths occurred amongst the Alutiiq people in the 18th and 19th centuries. Russian exploitation of resources and the Alutiiq people continued until 1867 when the Alaska Purchase transferred the territory from Russia to the United States. American interests concentrated on whaling, the fur trade, and the development of commercial fishing. In 1888, the first salmon cannery was built in Chignik. By 1890, commercial salmon fishing had become the most profitable industry in the area and has continued to the present.

Castle Cape has historically served as a distinctive landmark for mariners navigating along the treacherous coastline. The landmark is so well known that the U.S. National Weather Service uses Castle Cape as a geographical marker to separate the coastal waters forecast for zone area 150 between Sitkinak Island and Castle Cape, and zone area 155 between Castle Cape and Cape Sarichef. The National Weather Service Marine Program has a mission to provide marine forecasts and warnings for the U.S. coastal and offshore waters. In 1870, a congressional resolution was introduced that required the Secretary of War to take meteorological observations and to provide notice of the approach of storms. A national marine weather program within the U.S. Army Signal Corp began on January 23, 1873, when meteorological data from ship logs were routinely transcribed from vessels arriving in port. In 1890, the U.S Weather Bureau became a civilian agency in the Department of Agriculture. In 1901, the U.S Navy began making marine weather forecasts for the North Atlantic and in 1904, the responsibility of marine forecasting was transferred to the U.S. Weather Bureau. In the early 1900s, the Norwegian cyclone model provided the first glimpse of the structure of the atmosphere across the mid-latitudes. This meteorological advancement and the increase in shipboard observations for the first time provided the ability for meteorologists to create a crude map of the state of the atmosphere. During World War II, the U.S. Navy established a marine weather center and the U.S. Coast Guard established manned ocean weather stations. In 1957, the U.S. Weather Bureau started to publish the Mariners Weather Log addressing marine issues that is still published today. The U.S. Weather Bureau became the National Weather Service 1970 and individual weather forecast offices, including three in Alaska, are responsible for issuing marine forecasts and warnings for nearshore coastal waters. Read more here and here. Explore more of Castle Cape here: