NASA images from one of the world's hottest volcano regions
The three largest volcanoes visible at image centre are Kliuchevskoy, Bezymianny, and Ushkovsky (see below for annotated image).
Klyuchevskoy is the most active volcano, with geologic, historical, and observational data indicating no major quiet periods since the volcano formed approximately 6,000 years ago. A thin ash and steam plume extends to the east-southeast from the summit of Klyuchevskoy, typical of activity reported at the volcano from early May 2015, when the photo was taken. The flanks of Klyuchevskoy are also covered with dark ash deposits, in contrast to the snow-covered flanks of both Bezymianny and Ushkovsky.
The Kamchatka Peninsula has more than 300 identified volcanoes, with 29 considered active, as well as hot springs, and geysers as a result of subduction of the Pacific oceanic plate beneath the overriding Eurasia continental plate.
The NASA Earth Observatory has more information.