What to expect:

Stunning landscape but also crowded! For the sake of completeness, I'll mention Trang An here in the guide. We went there on our scooter. However, there were so many people that we didn't take a tour. We decided to go to Van Long Wetland Nature Reserve instead because it's much quieter.

If you are very short on time, and want to explore this stunning area, you can do it as a one-day-tour from Hanoi, which I will link below!