Tell Me, Wave, Where Did You Come From? Who Made You?

In his book, The Wave Watcher's Companion, Gavin Pretor-Pinney says those Micronesian sailors could "feel" the waves telling them where there was land. The waves pointed back to land that was 30, even 40 miles away. The navigators wouldn't stare at the sea. Instead, they'd lie down on the boat's bottom and, resting against the wood, they'd tell their companions, "the land is behind us" or " I can feel the land up ahead." But how did they know?