No need to make ressies. It is all part of the package.
When you get there you will check in and get your photo taken for your badge. Then they will walk you out in groups and explain to you the rules and such. You will then get your complementary picture taken. The guide will then take you over to the equipment area where they issue a snorkel,mask and towels. They then take you to the area where you get fitted for a vest or wetsuit (your preference). Finally, they take you to the locker area where you chose a locker and lock all of your personal belongings up.
FYI
if you are doing a dolphin swim they will make you take off all of your jewelry and you must wear your id card at all times (they provide a lanyard). Just tuck it in your vest.
You will have the name of your cabana and a time on your id card. Go to the cabana at that time where they will instruct you on your dolphin swim. They will escort your group out into the water where the dolphins are.
Also, no need to bring sunscreen, they have special sunscreen (for free) that they want you to use because it is environmentally friendly and safe for the marine life.
When lunchtime comes, just get in line and pick what youd like. They will swipe your id card (its part of the package). Also, there are several souvenir stands around. When you get your ids done, they can put your credit card info on them so you can charge stuff on them if you'd like.
Hope that helps, you will have lots of fun!!!
Susan