Towering limestone pillars emerge 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. Halong Bay's spectacular scatter of islands, dotted with wind and wave eroded grottoes, is a vision of ethereal beauty and northern Vietnam's number one tourism hub. Most visitors choose cruise-tours that include sleeping on board within the bay, while a growing number are deciding to eschew the main bay completely. Halong Bay attracts visitors year-round with peak season between late May and early August. January to March is often cool and drizzly, and the ensuing fog can make visibility low, but adds bags of eerie atmosphere. From May to September tropical storms are frequent, and year-round tourist boats sometimes need to alter their itineraries, depending on the weather. November's sunny blue-sky days and lack of crowds make it the best time to make a beeline here.