What is zavaritski caldera?

Zavaritski Caldera is a volcanic caldera located in the northern part of Iturup Island, part of the Kuril Islands chain in Russia. It is thought to have formed around 40,000 years ago during a large, explosive eruption that blanketed the surrounding area with ash and pumice. The caldera measures around 12 kilometers in diameter, and is filled with a large lake known as Lake Zavaritski. The lake is a popular tourist destination, known for its stunning scenery and diverse wildlife. The area surrounding the caldera is also home to a variety of other volcanic features, including hot springs, fumaroles, and lava flows.