If your landing at international air port and you must be. you will exit from picking up your bags and passing thur customs at doors to the outside where dozens of cab drivers will be waiting to take you to the water taxi terminal at the swing bridge in Belize city.
I think its about a 25.us taxi ride. the water taxi terminal office will sell you a ticket to San Pedro and It will take about an hour to get over by boat. where you dock in the center of town. More taxis will be waiting to take you to your hotel.
unless your hotel is one of the many on the other side of the cut , ...What hotel are you staying at?

White Sands Dive Shop
https://whitesandsdiveshop.com/