There were a couple of times that trip when just leaving my brother behind came up in conversation! We know what he's like, so it wasn't a surprise.

The ice cave was definitely one of the trip highlights. and it's something you can only do in winter. When the ice is melting the caves can collapse (and one did exactly that last year, killing someone who should NOT have been inside it in August).

There are some black sand beaches in Hawai'i' and some Caribbean islands too. The ones we saw there looked different under the sun with stunning blue sea :-)