The Shiretoko Peninsula was registered as a UNESCO World Heritage Site in 2005, in recognition of the peninsula being the southernmost point where sea ice usually forms in the Northern Hemisphere.
From Shiretoko Cape at the tip of the peninsula, a series of volcanoes run down the peninsula, including Mount Shiretoko, Mount Unabetsu, and Mount Iō. It is part of the Chishima volcanic zone. The highest peak is Mount Rausu. The peninsula is 70 kilometres (43 mi) long and 25 kilometres (16 mi) wide at its base. It covers some 123,000 hectares (470 sq mi)
The peninsula is bounded on the northwest side by the Sea of Okhotsk and the southeast side by the Pacific Ocean. To the east, Kunashiri Island runs parallel to the peninsula. The Kunashiri can be seen from Shiretoko Peninsula. Kunashiri has been occupied by Russia since September 1, 1945, and disputed by Japan.
The cold Oyashio Current flows south along the peninsula.
The volcanic zone has made several onsen possible, including Seseki Onsen and Iwaobetsu Onsen.
The Oyashio Current has a profound impact on the weather of the peninsula. Shiretoko Peninsula has short summers and long winters. The current causes fog on the southeastern coast and sea ice in the winter. Snow covers the peaks from September to June, except the very highest peaks, which retain snow all summer long.
The Shiretoko Peninsula is home to many species of both conifers and broadleaf trees, including the acorn-bearing Quercus mongolica (mizunara). Siberian dwarf pine trees grow above 1,000 metres (3,000 ft). Red foxes and sika deer also inhabit the area. There are a large number of Ussuri brown bears. The upper reaches of Mount Rausu, Mount Onnebetsu, and Mount Shari are the only known breeding areas of Arctic warblers in Hokkaidō. Sea eagles flourish here, and seals can be often seen on the coast.
Whale watching is a popular attraction for tourist. Thirteen or fourteen species of cetaceans have been recorded in the area. Especially for orcas, or killer whales, the waters surrounding the peninsula are regarded as one of the most significant habitat areas in the northwestern Pacific. There was a notable mass stranding of twelve animals in February 2005. Nine animals died.
Shiretoko Peninsula is one of the few places where groups of male sperm whales and Baird's beaked whales can be spotted from the shore. Other frequently seen species include minke whales, Pacific white-sided dolphins, Dall's porpoises and harbour porpoises. A possible new form of giant beaked whale are using these areas as well.
Endangered populations of humpback whales and fin whales in the Sea of Okhotsk have started to recover in recent years. Some beluga whales, or white whales, that are thought to be vagrants from endangered population in the northern Sea of Okhotsk do occur, specifically a sub-adult individual that continuously appeared at the town of Shibetsu for several years in the 2000s. North Pacific right whales, the most endangered of all the great whales, have been observed close to the shore mainly on the Sea of Okhotsk side of the peninsula. From June 21 to 23, 2015, the first ever sighting of a bowhead whale in the Japanese EEZ occurred (the first record of the species in the nation was of a catch record in Osaka Bay on June 23, 1969). Several records from whaling days show blue whales to have been harpooned and landed at Abashiri port, though this species normally does not enter adjacent seas and are now thought to be almost extinct in Japan´s waters. As a deep, productive water, some species of beaked whales favor the area including Cuvier's beaked whales, Stejneger's beaked whales and others. Baird's beaked whales, the largest of this group, are most frequently observed close to shore. An unidentified form or subspecies of beaked whale is known to inhabit the waters off Shiretoko Peninsula and Abashiri. Long-finned pilot whales which once inhabited the waters around Hokkaido are thought to have become extinct in the 12th century, but unconfirmed sighting of short-finned pilot whales have been reported in Nemuro Strait though the area is out of their normal range.
To protect the wild animals and pristine natural beauty of the Shiretoko Peninsula, in 1964 a great portion of the peninsula was designated Shiretoko National Park. Since then, the park has been subject to strict regulation as a nature preserve, and entering is prohibited.