Even if you don't play tennis it is well worth having a game just to watch the activities of the monkeys who live in the trees surrounding the tennis courts. They climb along the top of the tennis court fence and watch you play. They also chase each other and if you hit the ball out of court, too bad, its gone.
Unfortunately I didn't catch them on camera, only on video.
Equipment: Can borrow racquets and balls from the hotel
The children of Watamu gather just behind our guesthouse every evening for soccer on the beach. We watched them play for a short time. It is an organized event with referees and people watching on the sideline. Smaller children gather to the side to play unofficial games of their own. It is quite a village event.
Equipment: You can join in for practices, but usually not for the real games.
The Sun Palm Hotel in Watamu is offering horse riding treks. I went for a 1-hour trek with 2 friends, and we were very happy with the horses. They were well trained and in good condition. My friends had no horse-riding experience, and they each had a person with them who was leading them as they were a bit nervous.
So we were well looked after and really enjoyed the ramble around the forest and the villages.
Equipment: Seeing that the climate is a bit different to Ireland, where I am usually ride, they are not as strict on the outfit that you need to wear as they would be in Ireland, and didn't make us wear a helmet or high riding boots.
You should make sure though that you wear long trousers and proper shoes, rather than flipflops and shorts :-). They will provide you with leather leggings for you to wear during the ride.