I would not know anything about that! The mountain I live on is not a volcano...or, if it is, I do not think anyone knows about it.

[Perhaps there could be lava inside, and it's just never erupted yet? But Ingo doesn't know how volcanoes work, and even if that is possible he suspects it isn't true of Mount Coronet.]

We are near the coast. Some of the caverns are underwater, sometimes, though I am certain they would not have placed us in one of those!