Just like with the insect repellent, you can purchase sunscreen onboard, but you're never guaranteed to get your favorite brand. What you are guaranteed is to pay quite a bit more than you would on land. To save some money and ensure your burn-free comfort, bring your own sunscreen. Pack it in a plastic bag to keep your other packed items safe from leakage. Choose a sunscreen that holds up well in water if you plan on spending time in the pool. You probably know what kind of sun protection factor, or SPF, your skin needs to remain burn free. Anything over SPF 15 is considered sunblock, and if you have fair skin you should err on the side of caution.
Just because you have sunscreen doesn't mean you'll be good about using it, so there's always a chance that you may get sunburned. If this happens, you'll be glad you packed some aloe-based lotion or pure aloe gel to provide some relief. Aloe soothes sunburned skin and helps to restore moisture.