Blue Magic on  Biševo (Croatia). &#x27;Of the numerous  caves around the  remote limestone island  of Biševo, the Blue  Grotto (Modra Špilja) is the  most spectacular. On a clear morning,  the sun’s rays penetrate  through an underwater hole  in this coastal cave, bathing  the interior in a mesmerising  silvery-blue light.  Swimming inside is a surreal  must-have experience –  worth a trip to this far-out  island. http://www.lonelyplanet.com/croatia