The GTC (Great Telescope Canaries) sees first light today. Apart from the sheer size (10.4 m) of its mirror and from the science it will deliver, the GTC is remarkable by its location at the Roque de los Muchachos Observatory 2426 m high at the rim of the Caldera de Taburiente in the island of La Palma. La Palma is also, for a number of reasons, also interesting for geologists. In that regard, it made headlines a couple of years back due to a paper about the risk of a collapse of the island which could cause a devastating tsunami. Oh, and it's also a really nice place for a holiday.