SPF 50 is adequate. Anything higher only marginally improves the protection. For example: * SPF 15 blocks 93% of UVB rays * SPF 30 blocks 97% of UVB rays * SPF 50 blocks 98% of UVB rays Also there is a difference between UVB and UVA It's not just the SPF that is important. It's also important how you apply and use the suncream is very important. * Apply 30 minutes before going outside * Reapply often, every two hours * Make sure you put enough on.