Russia

Alaska might be wrong - external link says it's originaly from a russian site ( external link ) and gives the location as the Kamchatka Peninsula.

The Mutnovsky volcano tp be more precise ( external link ) and a search for that gives you external link and a picture of what looks like the same ice cave, only this time looking out of it instead of into it.

Somehow I think I wouldn't feel comfortable there in the summer!

Somewhere in Alaska external link external link