Sung Sot Cave, Halong Bay

Cave is a one way route. The inside is filled with stalactites and stalagmites. The ceilings of the cave are carved from a prior earthquake where the ocean mixed with the minerals of the cave and created an acid that ate through the rock. There's free toilets at the beginning and end of the cave. The cave inside is cool and similar to an air conditioned room. There's a good viewpoint at the beginning and end of the cave that looks out to the water and the islets.

I visited the cave as part of a Ha Long bay cruise, like I'd assume most people that visit the cave. The cave is really beautiful, with lots of different sections in it that you need to walk through. It's actually much larger than I was expecting. The entire tour probably took us 30 to 45 minutes. There's an initial 118 steps to get up into the cave, and then further upwards climbing towards the end that takes a decent effort, so if you have mobility issues or aren't somewhat fit you might find it difficult. The weather was great when we visited, albeit quite hot, so walking through the cave and on the rock floors/steps was fine, but I could see how on a humid or wet day it could get very slippery and possibly dangerous if improper footwear is worn (I was in flip-flops so thankfully the ground was dry)!