Take a short boat ride from Sorrento to the island of Capri, once the private retreat of Emperor Augustus and his successor, Tiberius. You can explore the ruins of Tiberius's 1st-century Villa Jovis, a retreat that was—according to his critics, at least—the scene of outrageous acts of debauchery. To this day Capri remains a haven for playboys and movie stars hopping around the Tyrrhenian Sea on their yachts. The Blue Grotto is among the island's best-known attractions. Hire a local rowboat to traverse this legendary sea cave and its electric-blue water.