So what's your favourite sunscreen? We use Ultrasun or P20 once-a-day sunscreen, in SPF20 or SPF50 grades.  If you're super-diligent about applying it properly everywhere, it works!  And it isn't too greasy, so sand brushes off fairly easily.

I read an article online the other day that said a few countries have banned the sale of sunscreen because a chemical in it is supposedly damaged their underwater reefs.