Coppertone Ultraguard Waterproof SPF 70 broad spectrum sunscreen is the very best sunscreen I have found for a long day in the sun (particularly if there is water involved). I burn extremely easily- to the point that I wear a light sunscreen every day in the summer because otherwise I will burn walking from my car into the grocery store (or wherever). But when I'm going to be in the water or out for an extended period of time I turn to Coppertone Ultraguard Waterproof SPF 70.
I used to use the SPF 50 of the same line, and people who think the extra SPF doesn't help aren't people who burn easily. Trust me, you can tell a difference. This works better. I also think it doesn't smell nearly as bad as the SPF 50. It still smells a little funny- a bit like rubber- but a funny smell is a price I'm willing to pay for good protection. It costs a little more than the SPF 50, but it is worth every penny.
Another good thing: This is a broad spectrum sunscreen: meaning it protects against UVA and UVB rays.
This is a truely waterproof sunscreen- to the point you have to scrub to get it off in the shower after a day at the lake or the beach.