Only after the (bad) experience I had with my Halong Bay tour that I found out it's so easy to go to HB on my own.
With a DIY trip, you wont have to worry about getting cheated by the tour operators. You can choose your itinerary (routes) and take your time to truly enjoy the beautiful attractions.
Here are some tips:
1) Getting from Hanoi to Halong Bay:
Take a minibus from Hanoi (Gia Lam bus station) to Bai Chay bus station [every 20 minutes; journey takes around 3.5 hours].
2) Getting around Halong Bay:
Once you reach Bai Chay wharf, you will see many boat companies. You can shop around for prices (and check out their boats) before renting (the prices are roughly the same though).
If you are going in a group, its definitely worth hiring the whole boat (VND380,000 for a 6 hour tour).
For boat companies and prices:
For routes (these are standard routes offered by all the companies):
Please take note of the caves' opening hours (around 8am - 5pm) when choosing the routes. The boats start operating around 6-7am.
These looked sooo tempting -- but there was so much to see and ... obviously you can rent a swan, here on West Lake, and enjoy a slow paddle around. The place where you can rent these is very near Tran Quoc Pagoda.
Try Handspan Adventure Travel's Lagoon Explorer 1 junk for a comfy sailing around Halong. $124 for a 2-day cruise. Leave Hanoi at 8:30am on day 1 and back in Hanoi on day 2 at 4pm. Exclusive pier in Halong, you won't experience the chaos of the regular pier used by other Halong Bay junks. Lagoon Explorer 1 has only 3 cabins. About 4 crew members serving the needs of 6 people. Food onboard was great!
Handspan Adventure Travel: 80 Ma May St, Hanoi
Just East of West Lake (Ho Tay) is a small lake where you can get some exercise and see the sites at the same time. Not for the faint of heart.
This sure isn't going to replace the cyclo -- but you have to say that operating a boat's oars with your feet is creative!