Kurile Lake is a large caldera

Caldera

A caldera is a cauldron-like volcanic feature usually formed by the collapse of land following a volcanic eruption, such as the one at Yellowstone National Park in the US. They are sometimes confused with volcanic craters...

 containing a crater lake

Crater lake

A crater lake is a lake that forms in a volcanic crater or caldera, such as a maar; less commonly and with lower association to the term a lake may form in an impact crater caused by a meteorite. Sometimes lakes which form inside calderas are called caldera lakes, but often this distinction is not...

 located at the southern tip of Kamchatka Peninsula

Kamchatka Peninsula

The Kamchatka Peninsula is a peninsula in the Russian Far East, with an area of . It lies between the Pacific Ocean to the east and the Sea of Okhotsk to the west...

, within the Southern Kamchatka Wildlife Refuge in Russia

Russia

Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

.

It has an area of 77 square kilometres (29.7 sq mi) (the third largest by area of all lakes in Kamchatka and the second among the freshwater lakes, second only to Kronotsky lake). The lake has an average depth of 176 metres (577.4 ft), and a maximum depth of 306 m (1,003.9 ft). The lake is fed by snowmelt

Snowmelt

In hydrology, snowmelt is surface runoff produced from melting snow. It can also be used to describe the period or season during which such runoff is produced. Water produced by snowmelt is an important part of the annual water cycle in many parts of the world, in some cases contributing high...

, rain and a few rivers and streams: the Etimynk, Hakytsin, Vychenkiya and Kirushutk. From the lake flows the Ozernaya (Lake) river into the Sea of Okhotsk

Sea of Okhotsk

The Sea of Okhotsk is a marginal sea of the western Pacific Ocean, lying between the Kamchatka Peninsula on the east, the Kuril Islands on the southeast, the island of Hokkaidō to the far south, the island of Sakhalin along the west, and a long stretch of eastern Siberian coast along the west and...

 to the west. The magnitude of fluctuation in the water level is one to three meters (the highest levels are from May to June and the lowest in April). The average water temperature off the shore is between six and seven degrees Celsius in September.

In the north-east coast is the dormant volcano Ilinskaya

Ilyinsky (volcano)

Ilyinsky is a stratovolcano located in the southern part of Kamchatka Peninsula, Russia near Kurile Lake....

 (Elijah). There are a few islands in the lake, the largest of which, Samang, is 0.66 km². Other islands include Chayachy, Serdtse (Heart), Nizkii (Low), and Glinyanii (Clay). There are hot mineral springs in the area.

Volcanology

The Kurile lake caldera was formed by two large volcanic explosions, one 41,500 radiocarbon years ago and the other around 6440 BC.

The huge amount of material ejected during the second explosion, one of the largest ever, produced thick pyroclastic-flow deposits around the countryside, and some ash

Volcanic ash

Volcanic ash consists of small tephra, which are bits of pulverized rock and glass created by volcanic eruptions, less than in diameter. There are three mechanisms of volcanic ash formation: gas release under decompression causing magmatic eruptions; thermal contraction from chilling on contact...

 fell more than 1000 km away on the Asian mainland.

The pyroclastic-flow deposit is about 100-m thick at a location on the Ozernaya River, 3 km west of Kurile Lake, forming a spectacular curtain of cliffs, known as Kuthiny Baty ("vertical standing boat") because of its erosionally fluted formation.

The explosion of around 6440 BC is given a score of 7, the highest, in the Smithsonian Global Volcanism Program's Volcanic Explosivity Index

Volcanic Explosivity Index

The Volcanic Explosivity Index was devised by Chris Newhall of the U.S. Geological Survey and Stephen Self at the University of Hawaii in 1982 to provide a relative measure of the explosiveness of volcanic eruptions....

, making it one of the largest ever, ranked together with Santorini

Santorini

Santorini , officially Thira , is an island located in the southern Aegean Sea, about southeast from Greece's mainland. It is the largest island of a small, circular archipelago which bears the same name and is the remnant of a volcanic caldera...

, Changbaishan, Crater Lake

Crater Lake

Crater Lake is a caldera lake located in the south-central region of the U.S. state of Oregon. It is the main feature of Crater Lake National Park and famous for its deep blue color and water clarity. The lake partly fills a nearly deep caldera that was formed around 7,700 years agoby the...

, Kikai

Kikai

Kikai is a Japanese name.Placenames*Kikai Caldera*Kikai, KagoshimaPersonal names*Hiroh Kikai , photographer...

 and Tambora

Tambora

Tambora may refer to:* In music:**Tanpura, an instrument used in Indian classical music for continuous production of consonating reference notes **Tambora , an Afro-Caribbean percussion instrument...

.

Wildlife

The lake is the largest spawning ground for sockeye salmon

Sockeye salmon

Sockeye salmon , also called red salmon or blueback salmon in the USA, is an anadromous species of salmon found in the Northern Pacific Ocean and rivers discharging into it...

 in Eurasia

Eurasia

Eurasia is a continent or supercontinent comprising the traditional continents of Europe and Asia ; covering about 52,990,000 km2 or about 10.6% of the Earth's surface located primarily in the eastern and northern hemispheres...

 (if not in the world). Measurements of the numbers of salmon entering the lake and the spawning of juvenile fish are conducted by observation stations (manned by the Pacific Research Institute of Fisheries and Oceanography (Тихоокеанский научно-исследовательский рыбохозяйственный центр or ТИНРО)) which is located on the western shore of the lake.

On the shores of the lake brown bear

Brown Bear

The brown bear is a large bear distributed across much of northern Eurasia and North America. It can weigh from and its largest subspecies, the Kodiak Bear, rivals the polar bear as the largest member of the bear family and as the largest land-based predator.There are several recognized...

 are often sighted.

Tourism

Kurile Lake is a national wildlife preserve and a national monument. It is a UNESCO World Heritage Site in the listings of composition of the volcanoes of Kamchatka.

Tourist access is by small plane from Petropavlovsk to Ozernovsky, by truck to Pauzetka, then by 6-wheel drive army truck and on foot