Jumping from the roof of a wooden junk surrounded by the towering limestone karsts of Halong Bay might not be everyone’s cup of tea, but a refreshing swim in the blue green water is well worth it, even if from a ladder down the boat’s side. A few hours from Hanoi, Halong Bay is a World Heritage-listed area on the Gulf of Tonkin with a multitude of stunning islet pinnacles jutting out, some forested and honey-combed with caves. Your overnight cruise sails over their shimmering reflections and around its coves and lagoons at a serene pace, and you’ll pass other junks, fish hatcheries, and the odd peak-top pagoda. After a dinner of fresh seafood you can relax on the junk’s rooftop deck. Watch the sun go down before retiring to your cabin and being gently lulled to sleep.