[OC] A dolphin jumps out of the water as it swims alongside a boat.

The boat was like one that could tow a water-skier and we were going pretty fast.

I think like how ducks fly in a V shape to travel efficiently, the dolphin could "ride" along the wake of the boat

Id say the dolphins liked riding along with the boat as it's wake could let them swim faster like someone on a bike could ride faster if they rode downhill.