The northeastern extension of Ha Long Bay, beyond the heritage zone and beyond most cruise itineraries. The landscape is the same — limestone karst towers, hidden lagoons, sea caves — but the boat traffic drops away dramatically once you leave the central heritage zone behind.
Three-night cruise itineraries are usually required to reach Bai Tu Long properly. Highlights include Vung Vieng floating village, less curated than Cua Van and still partly inhabited; the long sandy beach on Quan Lan Island; and the largely uninhabited Bai Tu Long National Park, with hiking trails through jungle and viewpoints over the islands. Operators that run Bai Tu Long itineraries include several of the better cruise lines — expect to pay more, but you trade the crowds for genuine quiet.