Whether you sail or ferry into Hydra, the sparkling boat-filled harbour and the bright light striking the tiers of carefully preserved stone houses make for a scene you'll never forget. The harbour in high season is an ecosystem of its own, with yachts, caïques (little boats) and water taxis zipping in and out. The marble quay is a surging rhythm of donkeys, visitors, cafe denizens and boat-taxi hawkers. By night the scene becomes a promenade: grab a chair, order a drink and watch the world go by.