For a morning or an afternoon, a moment at the cascade of Nosy Be will relax you, this vegetation is different from what is usually found on the island, I had the impression to meet me in Reunion when I went there!
No need to go through an agency, rent a car or take a taxi. Located on the west coast of Nosy Be, to get there you must pass a path that is before the junction to go to Ambatoloaka. Attention, more than a path, it's a track, so do not plan to go there in the rainy season. After 15 minutes of track, you arrive at a barrier or you will have to pay an access fee of 2,000 Ar / person to access the waterfall. Keep your tickets, personally I was controlled 3 times ... Absolutely useless but the inhabitants of the place are unfortunately a little too aggressive on this side.