If you book your cabin thru the casino, and/or have a playing history with the NCL casino, you get free drinks in the casino (and at the casino bar). The entry level drink card allows you to get house drinks, beer,wine,sodas, juice, specialty coffee, and boxed waters. The more you play, you earn a higher level of drink privileges. So, a lot of casino customers use their casino drink card to fill in for drinks not available with the free at sea drink package. Personally, I always decline the free at sea package and just use my casino drink card. There are no gratuities associated with this card. I simply tip the bartender or server a buck or two for each drink.