Refers to someone who travels by raft, often used in the context of Cuban rafters.
El balsero remó con fuerza para llegar a la orilla antes de que anocheciera.
The rafter rowed vigorously to reach the shore before nightfall.
El balsero navegaba por el río con gran habilidad y destreza.
The boatman navigated the river with great skill and dexterity.