It is vital to apply enough sunscreen. In order to receive the protection offered by an SPF15
sunscreen, you would need to put on a 120 ml bottle every day you spent at the beach. Most people
do not use nearly that amount, which will reduce the SPF considerably. Moreover, the effectiveness is
like to diminish further when you perspire or wipe your skin with a towel. You should reapply sun
cream at least every hour after swimming, even if you are using a waterproof brand.