I would not take the boat over when I arrive: you would need to take a taxi over to the ferry site (it's only 10-15 min), it can be very crowded if it's getting towards the end of the day, and with all your luggage (you & it could get a little wet), it's just kinda a hassle. It's so much faster & easier to just hop on da plane and then you're THERE and ready to relax and start enjoying your vacay! If you take any island tours or just want to bop over to Belize City to the zoo or somethin' then I would take the ferry!