The island of Santorini is a giant volcano, a thousand shades of black, half submerged in the water, forming a half-moon around the visible part of the crater. What a contrast between the caldeira, which peaks at 300m above sea level before literally plunging into the Aegean, and the rest of the island, overrun by the country's finest vines and sloping gently towards pearly banks of red, black or white sand. Despite the summer crowds, the island works its magic.