If you're planning to take a trip from Hanoi to Halong Bay to check out the amazing views, don't miss a journey into Hang Sung Sot Cave. Many of the overnight tours include this adventure as part of the trip-and it's not to be missed. In addition to getting to pretend you're on another planet, there are these kind of bizarre, yet appealing, penguin garbage cans all of the place. Oh, and natural wonder. It has that, too. Tip: It was a little chilly when I was there, so bring a sweatshirt.