Getting there and away

Bus

Muang Ngoi is only reachable by boat.

Boat

Public boats leave Muang Ngoi for Nong Kiaow at 09:00 and 11:00 and cost 20,000 kip. Outside of those times, you will need to charter a boat -- it should cost about 300,000 kip one-way, or 400,000 round-trip. If that's too pricey, try to negotiate a fare onboard a boat that happens to be going from one to the other, usually for some sort of delivery. A fair price is around 50,000 kip/person.

Other public slow boat destinations include:

Muang Ngoi to Muang Khua: departs at 08:00, costs 88,000 kip and takes 4 hours – Note that this boat leaves infrequently, so be sure to get up-to-date info at the boat landing.
Muang Khua to Phongsali: departs at 08:00, costs 88,000 kip and takes 5-6 hours
Nong Kiaow to Luang Prabang: departs at 10:00, costs 110,000 kip and takes 6-7 hours

Boats can also be chartered to these destinations at much higher cost.