Weather Everything Mascara by Bare Escentuals. That stuff won't budge through swimming, rain, tears, sweat, whatever. However, you better have some good eye makeup remover for waterproof mascara, along with some cold cream or you will still have it on the next day.
I also like the Blinc Kiss Me mascara and like how it comes off with just soap and water with a little pressure. I don't like the little tubes that are left in my sink, however.