Ow, ow, ow. Done that. California baby is also waterproof, but I don't know how it compares to Bullfrog in pleasant-ness of use (it's goopy with a capital G). If you want a spray, you might choose one made for skin (not hair) and with zinc/titanium as the sunscreen - having been warned that you'll need to wash it out really well! The new "clear" zincs are easier to deal with. BurnOut Eco-Sensitive Zinc Oxide Sunscreen SPF 32 is one I've tried recently. It's waterproof and really easy to spread.
If I were using a spray or cream, I'd part my hair many times and spray or dab in the part and rub it in. Good luck.
http://science-yhairblog.blogspot.com/