We had the opportunity to stop at the famous Grotta Azzurra (Blue Cave), where Emperor Tiberius used to swim, however the line was about one hour to get into the cave, so unfortunately everyone on the boat opted out. However, if you are interested in doing it, it costs 14 Euro per person and, once it is your turn to go in, you will transfer into a small wooden boat and bend down below the sides of the boat in order to pass through the cave opening.