Pick a licensed operator with recent reviews, and check what the price includes. Many cruises serve pork; request halal, seafood or vegetarian meals when booking.
Overnight is better
One night on Ha Long or Lan Ha Bay lets you see sunrise on the water and avoid five or six hours in a car on a single day.
Start early
Leave Hanoi by 7.30am for Ninh Binh and Duong Lam to beat tour buses and enjoy the soft morning light.
Weather and boats
Fog and wind occasionally delay bay cruises in late autumn. Keep a flexible day in your plan.