The Sava region (known for its four principal towns, Sambava, Antalaha, Vohémar and Andapa) is disconnected from the rest of the country, with the exception of the airports at Sambava and Antalaha, and one rough road: the 157km piste between Ambilobe and Vohémar, for which you will need a 4WD, has been badly degraded by the rains of 2015. Count on 10 hours, or 18 by taxi-brousse. It is virtually impassable in the rainy season – the huge trucks you'll see navigating the potholes can take up to a month to get through at that time of year.
The only overland route from Maroantsetra to Antalaha is on foot, requiring several days of trekking. Having said that, the airports make the region’s principal attraction, the superb Parc National de Marojejy, easily accessible. The area is economically better off than most, as its principal crop is the valuable vanilla bean. You can enjoy a decent beach break here, too. So this is a pleasant place to be marooned, particularly as there are very few tourists to be found.