This is one of the most active volcanoes in the southern Kamchatka Peninsula, Russia. The system consists of several craters and a caldera, which together form an enormous complex volcanic system that extends almost 100 km across.

The caldera formed when the lava below the surface moved out, which made it collapse into itself. Over time, water filled in the space and became hot and acidic due to rock-water interactions. Today, the caldera has an elliptic shape of around 10 x 12 km (6 x 7 miles) in diameter.

The area is also home to many volcanic cave tunnels that can be explored. The volcanoes have overlapped over time, offering a magnificent view to the tourists.

Photo by Jody Bourgeois.