Vikings used an ingenious method of navigation on long sea voyages by carrying trained ravens and releasing them when they were far from shore. If a raven circled the ship and returned, it meant there was no land within its sight, so the crew continued on their current course. But if the bird flew off in a straight line and didn’t come back, the Vikings knew it had spotted land and they followed its path. This simple but clever technique—famously used by the explorer Raven-Flóki—allowed them to