Paddles are tools which allow players to move around on watercraft, either punts or rafts. They can be made or bought from a general store/fishing shop; in the former case, one board and an axe is needed. Paddles can move players in deep water, so they are superior to sestas.
Inability to make a paddle[]
Starting on an island that has no settlement will make it impossible to obtain an axe if you did not start with one. You will not be able to make it to the part of Living in the Wild which gives you one, nor will you be able to barter for one. Without an axe you cannot make a paddle and without a paddle you will not be able to leave most islands. Stone axes cannot produce boards, and without a board you cannot produce a paddle. The best way to avoid this is by not starting on an island.