As Europe's elite quietly leave the crowded Riviera behind, one Croatian island is emerging as the destination where luxury travelers prefer to end their Mediterranean summer. Every decade the Mediterranean crowns a new destination that quietly captures the imagination of sophisticated travelers before the rest of the world catches on. Saint-Tropez enjoyed its golden era. Capri remains timeless. Mykonos became the social capital of the Aegean. Today, an increasing number of yacht owners, en