Krenitsyn Volcano

Krenitsyn Peak stands on Onekotan, an uninhabited island in the northern part of the chain between Kamchatka and Hokkaido, and it is a textbook nested caldera: an older volcano collapsed leaving a ring, the ring filled with water to form Koltsevoye lake, and a new cone grew from the lake floor to 1,324 metres, so the mountain now stands on an island in a lake in a crater, ringed by the wall of the older volcano. Geologists and photographers describe it as among the most perfectly formed structures of its type anywhere. It last erupted in 1952. Nobody lives on Onekotan and there is no airstrip or harbour, so it is seen from expedition vessels working the chain in summer, with zodiac landings when swell allows - which is often not. Border zone permits are compulsory and arranged by operators well in advance, and the weather here is among the foggiest in the Pacific.

What you actually see

• The nested structure - a cone on an island in a lake inside an older caldera.
• The scale - a 1,324-metre peak ringed by the wall of the collapsed volcano.
• The isolation - an uninhabited island with no harbour or airstrip.
• The 1952 eruption - the volcano's last recorded activity.

When to go

July to September, when expedition vessels work the chain. Access is only aboard such a voyage; landings depend entirely on swell and fog.

Honest expectations

There is no independent way to get there - expedition vessel only, expensive, and booked far ahead. Fog in this chain is near-constant and many voyages never see the peak. Landings are cancelled by swell. Border permits are compulsory and take time.

Nearby

Paramushir and Ebeko are north; Kamchatka is beyond them.