Sung Sot Cave (Surprise Cave)

Sung Sot, the 'Surprise Cave', is the largest cave in Ha Long Bay and the high point of most Route 2 boat trips. Boats tie up at Bo Hon Island and you climb a stone staircase to the entrance, high in the cliff, before a paved path loops through two huge chambers filled with stalactites, stalagmites and the bright lighting that Vietnamese caves favour. The path is about 500 m with plenty of steps, and the cave is warm and humid inside. Expect crowds in the middle of the day, when several tour boats arrive at once; on the way out, the viewpoint at the exit looks straight down over the boats moored in the bay below.