Bongoyo Island is an uninhabited island in Tanzania, situated 2.5 km north of the country's largest city, Dar es Salaam. It is the most frequently visited of the four islands of the Dar es Salaam Marine Reserve and a popular daytrip for both tourists and Tanzanian residents alike for snorkelling and sunbathing.
The island lies close to the Msasani Peninsula and is reachable by means of a 30-minute boat ride from the mainland. The point of departure for most visitors to the island is 'The Slipways' hotel complex on the western side of the Msasani Peninsula.
Wikipedia https://en.wikipedia.org/wiki/Bongoyo_Island
Coordinates -6°41'52.645" N 39°15'55.08" E