There are three white coral sand beaches south of Mombasa. If you’re traveling in the high season, it’s smart to make advanced bookings. High season is January, April through the beginning of July, then August through the beginning of September, and December.
Shelly Beach is the closest beach to Mombasa. You can walk to the beach from the Likoni ferry in about 30 minutes, or hitch a ride short ride from a matatu. Unfortunately there arent any good quality or nice resorts on this beach and Diani offers so much more.
The next beach south of Shelly is Tiwi Beach. Tiwi is the least developed of the beaches near Mombasa, therefore is the best bet for budget travelers, but not really recommended unless you are looking for backpacker options.
Diani, south of Tiwi, is perhaps the most developed beach in all of Kenya. Diani Beach is a major beach resort, lying on the Indian Ocean coast of Kenya, 30 km south of Mombasa. It is located along a beautiful white-sanded beach which is about 25 km long and it merges with the small town of Ukunda which is home to a small airstrip. The area is known for its coral reefs, the closely located Shimba Hills National Reserve and for its black-and-white colobus monkeys. It has high-class restaurants, hotels and has two shopping centres.