Pregnant on a cruise

JV • Just got the BFP to complete our "yours, mine and ours" family :) married 10/12/12 <3
Has anyone been on a cruise while pregnant? We had already booked a week long one  to the Florida keys and the Bahamas with my husband's family (his parents, brothers, cousins, grandma... They all go do big stuff as much as possible every summer, I love them!) but we didn't really expect me to be pregnant by then! I'll be 18 weeks while on the ship. At least I'll be past the first trimester, but not quite into being huge and uncomfortable (this is my third baby, yay cute baby bump!) I've already checked with the cruise line and I'm okay to sail as long as my Dr signs off on it. :)
Anyway, any tips?? I'm so excited, but I've never been on a cruise, much less pregnant on one!