Short answer
It is reached on bay tours that include kayaking or bamboo boat rides. The passage is low and tide-dependent; follow your guide and keep your head down.
01What to expect
The tour boat anchors near the island and you continue by kayak or in a bamboo or tin rowing boat paddled by a local. The 'dark' part is the narrow, low tunnel where the light fades; the 'bright' part is the lagoon on the other side, a circle of cliffs open to the sky, with still water and birds overhead. The whole passage is around 70 metres.
02Tide and safety
- At high tide the arch may be too low to pass, so the timing is set by the tide table
- Wear the life jacket you are given and keep hands inside the boat in the tunnel
- Watch for sharp rock and oyster shells on the walls
- Do not attempt it alone in a rented kayak
03Same name, two caves
You may also see a Hang Sang Toi listed on Ha Long Bay cruises from Ha Long city. That is a different cave in the Quang Ninh part of the bay. When booking, ask which one the trip includes.
?Questions people ask
Do I need to be a good kayaker?
No. The paddle is short and calm, and you can choose a rowing boat with a local instead.
Is it suitable for children?
Yes, with a life jacket and an adult in the same boat. The dark section is brief.