Russian writings claim Russian knowledge of the island from the early 18th century. The Russian explorer Ferdinand P. Wrangel, for whom the island was later named, determined its location from accounts of Siberian natives but did not land there during his mapping of the Siberian coast in the early 1820s. Russian fur traders subsequently visited the island, and it was sighted by U.S. vessels in 1867 and 1881. Survivors of a sunken Canadian ship reached Wrangel in 1914, and the leader of the expedition, Vilhjalmur Stefansson (Stefansson, Vilhjalmur), created an international incident in the early 1920s when he claimed Wrangel for Canada without authorization. The Soviet Union then annexed the island, and permanent occupation began with the landing of Chukchi and Russian families in 1926. Wrangel Island State Reserve, established in 1976, occupies 2,700 square miles (7,000 square km) and contains polar bears, walruses, and reindeer. The reserve was designated a UNESCO World Heritage site in 2004.