That is our life for 6months/year. And with summer sport it is harder & harder to avoid sun, here in Aus 11-3pm are the "high risk" hours, (10-2 if in a place that clocks don't change)
We use sunscreen lots (found Hamiltons the best but it is an Aussie one) & my fair headed red-head, can play cricket for 3 hours or be at the beach for 3hours (even in the middle of the day) with that one & not get burnt... he burns in 10mins without sunscreen, so I know it works well KWIM. My boys have a rash shirt & board shorts for swimmers, infact I don't think we ever (DH & me included) have ever had our shoulders & thighs exposed... neck to knee & elbows all the way around here.