The Halong Bay area in northern Vietnam is a UNESCO world heritage site. Close to it, you can find Lan Ha Bay and Cat Ba Island. This area is recognized for its many limestone islands (a few thousand) in the sea.
We have started our trip on Cat Ba Island, hiking through its National Park, a UNESCO Man and Biosphere Reserve Area. Our guide took us around 15 kilometers to a very small village where we had a late lunch. From there, we cycled to a small port and were taken to Nam Cat - our accomodation for the night. On the next morning, we started a 2 day boat cruise through Lan Ha and Halong Bays. We have seen the swimming villages and did some kayaking into caves. Everything was organized by Mr. Tung, the manager of Cat Ba Ventures.
Unfortunately, the wheather was not always the best and we did not really have a clear sky. Nevertheless it was amazing and nothing I would regret. Definitely a place to re-visit in the warmer and clear months.