Towering limestone pillars and tiny islets topped by forest rise from the emerald waters of the Gulf of Tonkin. Halong translates as 'where the dragon descends into the sea' and legend tells that this mystical seascape was created when a great mountain dragon charged towards the coast, its flailing tail gouging out valleys and crevasses. As the creature plunged into the sea, the area filled with water leaving only the pinnacles visible. The geological explanation of karst erosion may be more prosaic, but doesn't make this seascape any less poetic.