白藤江
History shows that Hạ Long Bay was the setting for local naval battles against Vietnam's coastal neighbors. On three occasions, in the labyrinth of channels in Bạch Đằng River near the islands, the Vietnamese army stopped the Chinese from landing. In 1288, General stopped Mongol ships from sailing up the nearby Bach Dang River by placing steel-tipped wooden stakes at high tide, sinking the Mongol Kublai Khan's fleet.