Ha Long Bay is recognized UNESCO as a World Heritage Site and is definitely one of the great wonders of the world. It includes over 1,500 islands and islets. It is well known for its limestone caves.
There are many travel agency that offers tours to Ha Long Bay. You can find them ranging from $99/person for a 2D/1N on a standard junk to $555/person for a 3N/2D on a luxury junk. It is also possible to take a 1 day trip to Ha Long Bay for $55/person on a standard junk, however, if you don't plan on visiting Cat Ba island/beaches and all of Ha Long Bay's caves, then a one day tour is enough.
You can bargain for a junk boat at the marina. We were able to bargin a standard junk for $1.1M VND = $52 USD for a 4 hour tour. It was nice to have an entire boat, with a crew of 2, for just the 5 of us. Of course, this was only the boat itself. We had to purchase everything else seperately. I believe it was $5 USD entrance fee to the caves.
Lunch (a la carte) was provided on the boat. There are no prices on the menu so we had to asked the captain how much each items cost before ordering. Even though we didn't want to order anything, the captain insisted we order something before sailing, that way, lunch will be ready after we finished exploring the caves. It's better that you order something small (2 or 3 items) off the boat's menu and you can order the rest of your lunch at the floating fish market after (pictures below). The prices are more reasonable at the floating fish market and the sea foods are more fresh. The captain and his crew cooked and prepared the food on the boat for us.
On the way to the caves, we sail passed a rock, shapped like a dog =)
I only had a chance to visit 1 of the caves. I forgot the name of it but I believe it is the Thien Cung Cave.
That's it. Hope you enjoyed this post. More post to come on Vietnam later =)