From Dar there are many islands reachable with a small boat or a ferry. The ferry harbour is close to the fish market in the city center and from there leave all the ferries to Zanzibar and Mafia island for example.
We took a small boat from a private beach to reach Mbudya. The island is a natural park where really few infrastructures are build to provide a simple grill for fish and shields against the sun.

Mbudya is a small island surrounded by a coral reef. In the center of the island there are giant crabs hidden in the holes between the rocks that look like a solidified foam. The only thins I could see were rats :( Huge eagles were flying over the island but I could not understand where they were living.

About 50 meters from the beach there is an intense life under the water. Every immersion we were making we it was like reading a different page of a marine biology book. On this web page one can see some of the species I've see underwater (no idea about names).

Once we were back to Dar it was saturday night. From the hostel we could hear the music coming from the bars on the beach. Along the coast there are some nices bars with dance floors where people were sitting on the beach drinking. To move from one place to another was not safe to walk on the street during the night and it was necessary to take a taxi or a bajaji.