Caye Caulker is an island in Belize.
Most people ride a ferry to get to the island. But there are a couple of private boats anchored there, so hitching in and out is definitely doable.
On the island, everything is walkable. But for the heck of it, hitchhiking is very easy. There are almost no cars, but golf carts. Each golf cart can carry 4 people confortably, and more sacrificing confort. Half the carts are driven by tourists, that are unlikely to stop. The other half is driven by Belizeans working for the tourism industry. They'll almost always pick you up.