Navigation on the open ocean is extremely difficult. It is a skill that takes years to master.

Even with years of skill, an experienced mariner was still able to ground their ship on an unseen reef, underwater rocks, or a sandbar, because they didn’t know their precise location.

The main problem, which was unsolved for centuries, was determining your longitude.

Learn more about the longitude problem, and how it was eventually solved, on this episode of Everything Everywhere Daily.