If you can afford to get there - get to Pemba (Wimbe Beach), Isla do Ibo (Ibo Island - 100-odd kms north of Pemba) and Isla do Mocambique (Mozambique Island) - east of Nampula.
I lived there from 1994 to 1996 and had a ball. They can be difficult to get to, but (especially in Pemba) there are free/cheap camping sites on some very lovely beaches and lots of old Portuguese ruins.
Cheers
Brendan