White Island is New Zealand's only active marine volcano. Whilst in New Zealand, my daughter and I took a tour with White Island Tours out of Whakatane on the north coast of the North Island of New Zealand. Two hours there by boat.
It is a humbling experience to spend around an hour and a half in the crater of an active volcano. If you are ever in the area, you should consider taking the tour.
On a scale of 1 to 10, it rates an exhilarating 16!