How does GPS work?
Take Floki Vilgerdarson, the Viking explorer credited with discovering Iceland. He never left port without a cage of ravens. To check if he was nearing land, he’d release a bird. If it circled the boat, he knew there was no land nearby. But if it took off in a set direction, Floki and his crew would be close behind, knowing the raven was headed toward the nearest land.
The ancient Polynesians were no fools either. They could calculate their position from wave currents and made maps out of sticks and shells based on the positions of the brightest stars.