Kamen Opasnosti is a group of rock

Rock (geology)

In geology, rock or stone is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic...

s, located some 14 km southeast of Cape Crillon

Cape Crillon

Cape Crillon is the southernmost point of Sakhalin. The cape was named by Frenchman Jean-François de La Pérouse, who was the first European to discover it. Cape Sōya, in Japan, is located 43km to the south, across La Pérouse Strait....

 (the southernmost point of Sakhalin

Sakhalin

Sakhalin or Saghalien, is a large island in the North Pacific, lying between 45°50' and 54°24' N.It is part of Russia, and is Russia's largest island, and is administered as part of Sakhalin Oblast...

) in La Pérouse Strait

La Perouse Strait

La Pérouse Strait is a strait dividing the southern part of the Russian island of Sakhalin from the northern part of the Japanese island of Hokkaidō, and connecting the Sea of Japan on the west with the Sea of Okhotsk on the east....

 (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...

).
Kamen Opasnosti is a small group of bare rocks, devoid of vegetation. Its length is 150 m, width – 50 m, highest point – approx. 8 m.

The rocks were a great hindrance to marine traffic in La Pérouse Strait, aggravated by frequent dense fog

Fog

Fog is a collection of water droplets or ice crystals suspended in the air at or near the Earth's surface. While fog is a type of stratus cloud, the term "fog" is typically distinguished from the more generic term "cloud" in that fog is low-lying, and the moisture in the fog is often generated...

s in the summertime. To avoid possible collision, ships had to set some of their crew members on guard to locate Kamen Opasnosti by listening to the roar of sea lion

Sea Lion

Sea lions are pinnipeds characterized by external ear-flaps, long fore-flippers, the ability to walk on all fours, and short thick hair. Together with the fur seal, they comprise the family Otariidae, or eared seals. There are six extant and one extinct species in five genera...

s living on it. In 1913, a lighthouse

Lighthouse

A lighthouse is a tower, building, or other type of structure designed to emit light from a system of lamps and lenses or, in older times, from a fire, and used as an aid to navigation for maritime pilots at sea or on inland waterways....

was finally constructed on the rocks.