This will be our first cruise but, when we go to Hawaii, I take one container for each day. I believe the containers are in the 4-5 oz range. We (DH, myself, DD(7), and DS(4)) do end up using them. We reapply frequently. DS(4) has already had to have two suspicious looking moles removed. The kids have never had any sunburn. I hope we can keep it that way. We are a sunscreen loving family.