The Tension on a Boat

In a basic country, it has to be said heading to an island off an island. My guidebook tells me that you should never attempt to swim between these islands because the current in the water is way too strong. The engine on the boat splutters and there's a bit of smoke, but we're chugging along fairly steadily. We leave the bay and then hit the deeper water between the islands. This is where the strong currents are. Another five minutes and we're halfway. Suddenly, the water gets choppier and the boat rocks from side to side. A boy who had his hand in the water suddenly swept off the side of the boat and he flies behind my girlfriend