Curious Kids: how do ripples form and why do they spread out across the water?

The sea was calm — no wind, no ripples, no fish breaking the surface. A gray sky hung above, forming a dull mirror at the horizon. The fishermen of San Rafael II were returning from a fruitless night when they spotted a strange yellow buoy drifting ahead. It seemed to be moving on its own — or being pulled from below. As they approached, the boat’s engine began to fail. The water vibrated, as if an invisible current pulsed beneath the hull. Then they saw it: a frail figure standing on the buoy,