Mwewe Island officially, Mwewe Island Marine Reserve (Kisiwa cha Hifadhi Akiba cha Mwewe, in Swahili) is a protected, uninhabited island in the Pemba Channel under the Tanga Marine Reserves (TMRS) with the IUCN category II located within Mkinga District of Tanga Region in Tanzania.

The majority of mangrove species were discovered, with Rhizophora mucronata and Sonneratia alba predominating.

[3] On the east and southwest, in the direction of the mainland mangroves, the intertidal zone is considerably less widespread.

[4] South of Mwewe Island, there are comparatively less seagrass beds because of the heavy muck on the bottom, strong resuspension, and consequent turbidity.

In this area of the Bay, snorkelling revealed a substrate mix of muddy sand that was frequently excavated by critters that burrow, giving the bottom a rough texture and small hills.