Kenya offers numerous opportunities for the water sports enthusiast (in addition to the freshwater and deep sea fishing described elsewhere). Its warm sea water is ideal for swimming, in contrast to inland lakes and rivers which contain the risk of Bilharzia infection (not to mention being attacked by crocodiles!).
Snorkelling and Scuba Diving proably come at the top of the list here, and could be combined with a more leisurely dhow cruise, or more conventional boat trip.
Windsurfing, kitesurfing, water-skiing, parasailing, canoeing and kayaking are further water-based activities that are available here, both inland and on the coast, together with white water rafting, although at a less dramatic level than is experienced on Zambia's Zambezi River.
Finally dolphin spotting excursions can also include actually swimming alongside these gentle giants (although this is probably not a good idea if you undertake the related activity of whale watching here).