Ha Long Bay is a UNESCO World Heritage Site in Quang Ninh Province in northeastern Vietnam, a seascape of extraordinary beauty where nearly 2,000 limestone karst islands and islets rise from the emerald waters of the Gulf of Tonkin. Sculpted by millions of years of erosion into pillars, arches, and caves, the islands — many capped with jungle — create one of the most iconic landscapes in the world. The classic way to experience Ha Long is on an overnight junk boat cruise, drifting through the karst formations, kayaking into sea caves, and swimming from the boat's deck as the sun sets over the water. The nearby Cat Ba Island (accessible by ferry from Hai Phong) is the largest island in the bay and has its own national park, as well as budget accommodation for travellers who prefer a land base. Ha Long City (formerly Hon Gai) on the mainland is the main access point, reachable by road from Hanoi in 3–4 hours.