A highlight of the Halong Bay cruise was a stop at Hang Sung Sot or Surprise Cave. The cave was discovered in 1901 by French explorers and discovered to contain many naturally-forming rock formations. Locals have identified forms such as a dragon, a Buddha and a tortoise.
The cave was much bigger than I thought. Following the defined path, it took us about 20 minutes to walk through the various caverns, eaves-dropping whenever possible on other tour groups (because we lost our own guide) for interesting snippets about the cave, and attempting to take photographs in the dark.
We emerged out of the caves into a Halong Bay caught in the midst of a thunderstorm. Tourists were huddled tightly together in what little shelter there was available. After being squished around and already more than half wet, we decided to brave the rain and run to the jetty. I will always remember that mad crazy run down the rough hewn steps and the flooded bridge-paths to the jetty.