There’s actually no difference, and both Hạ Long Bay and Hạlong Bay refer to the same amazing location. 

The original Vietnamese is two words, "Hạ Long", meaning "descending dragon". However, both spellings are correct, with Hạlong Bay considered more informal. 

Don’t be confused if maps, cruise bookings, and travel sites use different spellings. Both still refer to the same place.

The UNESCO area of Halong Bay actually refers to 3 different bays: Halong Bay, Bai Tu Long Bay and Lan Ha Bay. As the three bays are all accessible from the same port (Tuan Chau harbour), and all three bays have virtually indistinguishable karst landscapes, cruises to the area are all advertised as Halong Bay cruises.

Most of the Halong Bay cruises have very similar looking activities - eg squid fishing, kayaking, tai chi, cave visits etc but there will be some differences depending on where your cruise goes.

For eg if you want fewer tourists, cruises going to Bai Tu Long bay and Lan Ha Bay will have the same karst landscapes as Halong Bay, but fewer tourists around. So that means when you do the cave visits, you'll also be crammed in with fewer people.

If you want to cycle around Cat Ba National Park, or visit Viet Hai village, then you can only do that with a cruise that takes the Lan Ha Baat route.

Personally we prefer the Lan Ha Bay route or the Bai Tu Long route as they see fewer tourists than the usual Halong Bay route. But it's really up to you! The key advantage of the Halong Bay route is that you get more choices of 5 star cruises (as traditionally the luxury cruises will take the Halong Bay route). But increasingly there are great 4-5 star cruises that will also sail the Bai Tu Long and Lan Ha Bay route.

With so much to see, a day trip or even a 2D1N cruise can feel rushed and leave you missing out on so many of the fantastic things there are to do here. Note that it takes 3-4 hours to get from Hanoi to Halong Bay (each way), so if you do a day trip or a 2D1N cruise, you don't get a huge amount of cruising time!

Usually when travellers do the 2D1N cruise, they will say that they wish they had done the 3D2N as they want to spend more time just enjoying the boat facilities and the views. So we highly recommend the 3D2N Halong Bay cruise so you get to actually relax and not rush from one activity to the other.

The best time to visit Halong Bay is from March to May, when the weather is pleasant, off-peak, and ideal for activities like kayaking and swimming. 

November to February is peak season, offering cool weather and misty views. But it is super crowded then! Book your cruise early. 

Avoid June to August, as these are the rainiest months. Most of Halong cruises have a lot of outdoor activities so it won’t be very much fun to visit when it rains. 

We would recommend avoiding Vietnamese public holidays (eg Tet) - even though the cruises are running then, the bay will be extra crowded and not very enjoyable as the caves are cramped and there will be lots of tourists around for the hikes, kayaking etc.

Most of the Halong Bay cruises will provide transport from Hanoi, as that is where all the travellers are usually based. If you’re planning to visit Hạlong Bay as part of a trip to Hanoi, or vice versa, the good news is that you won’t have too far to travel. The two northern locations are just 175km apart. 

To get from one to the other, most visitors will hop on the provided transport, which typically takes around 3-4 hours.