Known as Croatia’s most seductive island, more than three-quarters of Mljet is covered in dense pine forest, and is home to the picturesque national park. Grab the bus from town which is included with your park entry fee. Boasting two translucent saltwater lakes, Mljet island is home to the Mediterranean’s largest coral reef, making it the best snorkelling in Croatia.. Be sure to paddle or boat out to the middle of the larger lake to see the small island home to a 12th-century benedictine monastery. According to legend Greek god, Odysseus, was tricked into spending seven years on Mljet. Doesn’t sound so bad to us!