Hi Zabka
You go straight to the ship from the airport, there you register for your on board card which you use for all puchases on the ship, after that you are free to get off the ship and explore Bridgetown so long as back onboard an hour before sailing, don't worry about your girls, just stick to the tourist areas, the locals are very friendly.
We always do our own thing when getting off the ship, there is always a tourist office in the port area, they will direct you to local taxis, about six dollars each one way to local beaches, a lot cheaper than ships trips and can come & go as you please, on last day you have immigration to attend usually on board, after that you can go ashore depending what time you are due to go to the airport, Your main hold luggage has to be packed and outside your cabin by midnight for collection overnight, so you will have to carry hand luggage after leaving cabin. have been on OV2, very laid back ship, no dressing up for dinner unless you want to, You'll have a great time, a cruise is the best holiday ever.
Rob & Brenda

Thank you so much for your reply. It is much clearer for me now.

Could you also tell me if you have to pay any 'taxes' on each islands? Or can people from cruise ships just go to any islands without showing passports and have their passport stamped?

Hi Zabka
No taxes to pay, do not need a passport for trips but suggest you carry a photo copy of your passports main photo page & a copy of your insurance contact numbers just in case of the remote possibillity of being late back & missing ship or an unlikely accident occurs, just a sensible thing to do, Rob & Brenda
PS, Ships daily patter gives all local things to do & ships phone no's etc.