Petropavlovsk-Kamchatsky
You may easily spend a month in Kamchatka without seeing all you want: there is too much to see! Yet, the place to start with is always its capital Petropavlovsk-Kamchatsky and its surroundings. Then you may go to Esso, Tolbachik volcano, Mutnovsky volcano, or Mutnovskaya geothermal power plant.