The Gambians do seem to fill their little boats to capacity, so when inside one of these, you will find yourself perilously close to the water. Don't rock the boat! You do not want to be in the river, it is cold, dirty and full of crocodiles and hippos.
It is not that the local people are dishonest, it is in fact the monkeys who will steal anything that isn't tied down! So don't leave anything outside your room, such as shoes or umbrellas - they will most likely not be there in the morning!