Natural Wonders: Maly Semyachik and its Volcanic Lake

Even Russians call Kamchatka the edge of the world. The long peninsula in the Far East is also one of the world’s most active volcanic arcs, with 160 volcanoes spread out over 270,000 sq km.

Of those volcanoes, 29 are active and have been molding the landscape for thousands of years. Maly Semyachik — which means “small stone earth” — is one of the 29’s oddest and most beautiful.

The summit crater of this volcano hosts a startlingly blue-green lake, whose color tries to lure you in for a dip. But unless you want your skin to burn off, it’s best to study it from afar. The lake has almost the pH of battery acid.

The volcanic ridge with three volcanic cones. Photo: Shutterstock


The indigenous people of Kamchatka believed that the volcanic landscape was the land of the deceased. To them, smoke and ash either signaled a coming conflict or came from the dead lighting fires in their yurts.

A compound stratovolcano, Maly Semyachik is a modest 1,560m high. Its summit stands on a three-kilometre ridge with three volcanic cones; Ceno-Semyachik, Mezo-Semyachik, and Paleo-Semyachik. Four hundred years ago, an eruption from the Ceno-Semyachik cone, the youngest of the three, formed the crater that houses the robin’s-egg-blue lake.

Maly Semyachik lies within a large caldera, which is an old, giant cone whose sides have mostly collapsed. This 15 by 20km caldera dates back to the Pleistocene, which began 2.6 million years ago.

In 1946, V.D Troitsky discovered the crater lake during one of his many expeditions to Kamchatka. Today, the crater bears his name.

Photo: Shutterstock


The lake’s intriguing color has drawn curious scientists over the years. It is possible to scramble down the steep 200m side from the north. The temperature of the water isn’t too bad, 30˚ to 40˚C, but its pH is less than 0.5. To give a sense of what that means: Some scientists once paddled the lake in a rubber boat. The rubber didn’t react with the acid but their aluminum paddles dissolved and they had a hard time getting back to shore.

The blue color comes from sulphuric acid issuing from underwater fumaroles. The air is also full of corrosive fumes. You can breathe it for a while but you certainly wouldn’t want to live there.

Because scientists couldn’t use their standard analytic tools in this corrosive water, they resorted a method called photogrammetry. This combines mathematics, photography, and optics to create a three-dimensional model of an object. The Russian Geographical Society’s Kamchatka Expedition of 1908 was one of the first surveying missions to use this tool. 

Maly Semyachik last erupted in December 1952, but it was a small one. Researchers suggest that another is due soon. 

A stamp of Maly Semyachik's crater lake.

A 2002 stamp of the crater lake of Maly Semyachik in winter. Photo: Shutterstock