This was an expensive diversion. We were on a holiday near Sorrento and decided to visit Capri. The Blue Grotto (Grotto Azzurra) is probably one of the most spectacular features of this small island and probably a great natural wonder of the world.
You enter in a small rowing boat and have to duck as you enter the cavern. The effect of the sun's rays entering the cavern through the mainly submerged opening is a sight to behold. I was sceptical before entering but the effect is indeed stunning. It is very dark (of course) and flash is of little use so you have to have a good low-light camera or cleverly use the illuminated light as a reference. But be quick - the boats aren't in long and the ride is rocky!
GR Digital IV (ISO 154, f1.9 1/4 sec)