Situated on the southern point of the island is Kizimkazi fishing village, once the formost settlement on the East Coast of Africa, now best known for being home to several schools of Bottle-nosed dolphins and Humpback dolphins, which can often be sighted following a short boat trip from the village.
If you are lucky, you may be able to swim quite close to the dolphins, which can be a very rewarding experience. The trip is best taken in the afternoon to avoid the crowds of tourists in the morning, which in big numbers can seriously disturb the dolphins. Other species that can be viewed include stingrays and turtles.
Kizimkazi is also the site of a 12th century mosque, the earliest evidence of Islam in East Africa, and is thus worth a visit for both natural and cultural reasons. The trip includes transport, guide, boat, snorkelling equipment and lunch.
Other locations on Zanzibar also offer opportunities for dolphin watching.
Zanzibar's Northern tip is where it's all happening - the watersports, the night life and the maximum density of other tourists. Depends what you are after - activity or quiet.
Many visitors seem to be unaware that Zanzibar's West Coast offers equally good beach and watersport facilities to other areas, together with much closer proximity to Stone Town and the airport.