Take a Journey towards the Center of the Earth in a unique tour at Thrihnukagigur Volcano in Iceland. This tour is only available in the summer of 2012.
Loved this it was an excellent trip and so did the kids-
Hint and tip if you like caving there is a further camber that can be explored but you will need to state this when booking as you will need a special guild to do that part so it needs to be prearranged.
If you can do not miss it. an excellent day.