Boat / Ferry, Belize
If you don't want to go in your golf cart or walk, then catch a water taxi. They will get youmwhere you want to go in a very short time.
They are rather expensive though.
In Puerto Barrios you can take a small motorboat in the morning to Punta Gorda in the south of Belize. It costs about $15 and will take about an hour.
Transportation by boat is great and cheap; renting a car in Belize is quite expensive. The small electric cars on Ambergris are fun.