Day 4 The yacht will take you to the island of Vis, where history, the sea, and adventure come together in perfect balance. Here, you can enjoy snorkeling, explore mysterious caves, and learn to harness the wind in your sails. Visiting the Blue Cave on the island of Biševo may seem enticing, but during the high season, it might be better to refrain due to the many visitors eager to see the cave's water shimmering in all shades of blue.