Quick answer: a pre-booked private car from Hanoi to Ha Long Bay takes about 2.5 hours door to marina and is timed backwards from your cruise boarding. Every alternative is cheaper and every alternative involves more moving parts on the one morning your ship will not wait.
The four ways to reach your cruise
1. Cruise-operator shuttle
Included or cheap, but built around multiple hotel pickups from 6:30 a.m. — you spend an extra hour touring Hanoi lobbies before the expressway even starts.
2. Tourist bus / limousine van
The budget workhorses. Fixed departure times, drop-offs near (not at) the marinas, luggage in a shared hold. Workable for flexible solo travellers.
3. Private transfer
Door to gangway: pick-up at your hotel or straight from Noi Bai Airport, one coffee stop of your choosing, luggage handled, arrival timed to your specific boarding window — with margin calculated honestly.
4. Seaplane
Spectacular and priced accordingly; weather-dependent and luggage-limited. A treat, not a plan.
The boarding-time math
Most cruises board between 11:30 and 12:30. Working backwards: 2.5 hours of driving, a 20-minute stop, and honest margin for Hanoi’s ring-road traffic means leaving the Old Quarter around 8:30–9:00 — civilised, if your transport leaves when you do rather than when the last of five pickups is finally aboard.
Which marina?
Your cruise confirmation names it: Tuan Chau (most Ha Long cruises), the international port, or Got pier in Hai Phong for Lan Ha Bay itineraries — that last one is a different road entirely, which surprises people who booked “a Ha Long transfer” generically. We deliver to the named gate.