The dolphin is riding a wave created by the little bulb below the ship
All the lil waves behind boats are synonymous with the ship wasting its movement energy by displacing some water that could’ve been moved more peacefully. If you can minimize waves, you can use less fuel to go the same speed.
This is a US boat from before we invented various techniques to reduce the size of the waves
One of those inventions was the Bulbous Bow, which is essentially a blunt mass of metal. It would seem to shatter all principles of hydrodynamics to place this in front of the ship, but the placement is strategic, and they actually make ships faster by creating interferences in the waves that the ship would normally create at cruising speed, cancelling them down.