I've used Frontline for the past year on my lab, and it works wonders!! We kept checking our dog for ticks, and thought we had the majority of them, but as soon as we put the frontline on him, the next couple of days we were finding dead ticks everywhere! it's disgusting, but Id rather have the dead ticks than the live ones!
As far as being waterproof, don't let the dog swim for 24 hrs after applying. After that, he/she is good to go! Just make sure to apply it once a month. We dont apply it from September-February since it is colder.
Good Luck!!