Sung Sot Cave is a large natural cave on the first island of Ha Long Bay. It is part of Ha Long Bay boat and cruise tours, and inside are stalactites that look like a turtle, a heart, and a baby dragon. Visitors leave the boat and walk one way to the cave's opposite exit, taking about 20 to 30 minutes, with the whole route taking about 45 minutes and guides giving explanations at each point. There are many stairs, which is difficult for people with weak joints.