You don't visit Ha Long Bay — you cruise it

Effectively, yes. Ha Long Bay is a seascape of limestone islands, so the way you experience it is from a boat — there's no walking route through it. Cruises range from short day trips to overnight and two-night voyages, and the boat, its route and its stops make up the whole visit. Choosing the right cruise is therefore the key to a good Ha Long Bay experience.

A day cruise gives you a few hours on the bay and suits tight schedules, but you share the water with the crowds and miss the quiet dawn and dusk. An overnight cruise lets you experience the bay when the day boats have left — sunset, night on the water and a calm early morning — and is widely considered the better way to appreciate it if you have the time.

They're neighbouring bays with the same dramatic karst scenery. Central Ha Long Bay is the most famous and busiest; Lan Ha Bay, to the south near Cat Ba Island, and Bai Tu Long Bay, to the northeast, are quieter with fewer boats. Many of the better cruises now route through Lan Ha or Bai Tu Long specifically to escape the crowds while keeping the spectacular scenery.

Most visitors reach the cruise ports from Hanoi by road, a journey of roughly two and a half to three and a half hours depending on the port and traffic; a newer expressway has shortened it considerably. Many cruises include the transfer from Hanoi in their package, which is the simplest option, so it's worth checking whether transport is bundled when you book.

Typical cruise activities include visiting a limestone cave, kayaking or taking a bamboo boat among the karsts, swimming, climbing a viewpoint such as Ti Top Island for the panorama, and enjoying meals and sometimes cooking demonstrations or squid fishing on board. Overnight cruises add sunset, night on the bay and a peaceful early morning, often with tai chi on deck.

Spring (March–April) and autumn (September–November) generally offer the most pleasant weather, with mild temperatures and clearer skies. Summer is warm and good for swimming but brings the chance of storms that can disrupt cruises, and winter can be cool and misty. Because weather affects sailing, checking conditions and building in flexibility helps, whatever the season.