The Athi River drops about twenty-seven metres at Fourteen Falls, near Thika, over a rock face broad enough to split the water into a row of separate cascades, which is where the name comes from. How impressive it is depends entirely on when you come: after the rains it is loud enough to feel, and in a dry spell it thins out considerably.
Local operators run boats towards the base of the falls, and the ground around them is good for walking and birdwatching, with Ol Donyo Sabuk standing directly behind. An hour and a half from Nairobi, cheap, and the easiest way to get moving water and open country into a single day. Entrance fees, transfers, drinking water and a guide are included.