Transcription
Imagine you want to sail across the Pacific Ocean. Somewhere out there, thousands of miles away, is an island. It might be the size of a small town. It's surrounded by the largest ocean on Earth, and if you miss it, there's nothing on the other side except more ocean for weeks. And all you have is a small canoe. Let's figure out how you're going to do this.
You can't see where you're going. The island is so far away that it's hidden below the curve of the Earth. You could point your canoe in exactly the right direction, and you still wouldn't see land for a month. So, how do you keep going straight?
During the day, you have the sun. It rises and sets in roughly the same part of the sky, so you can hold your direction off of it. Easy. Except, the sun sets. Now it's dark. You're in the middle of the ocean, and you have no idea which way you're headed.
So, you use the stars. Like the sun, they rise on one side of the sky and set on the other in the same spots on the horizon. So, a particular star will always come up at the same point. If you know a star, you know your direction. But, one star only helps for a little while. It climbs too high in the sky, and then it's useless. You memorize the next one, and the one after that, and the one rising behind it. You build a chain of stars, each one taking over as the last one climbs too high. The navigators who did this memorize the rising and setting positions of dozens of stars. They held that entire map in their heads.
Impressive as this may be, there's a small problem. It's cloudy. The stars are gone. You're in the middle of the Pacific with no sky at all. This is where it gets crazy. Now you're going to feel the ocean. Out in the open Pacific, the swells, or the big rolling waves, travel in steady, consistent patterns for enormous distances. They're created by storm systems far away, and they don't change unless they run into something. Once you know the direction a swell is rolling, you can use it like a compass. You lie down in the canoe and feel the way the hull lifts and drops. If the swell is supposed to be hitting you at a certain angle and suddenly it's changed, you're the one that's turned. To make things more difficult, there can be multiple swells at once. You need to be able to recognize each one and tell them apart purely by the motion of your boat.
At this point, you can consistently stay on course, but another question enters your mind. How far have you actually gone? Direction is only half the battle. You also need to know how far you traveled, or you'll sail straight past your island in the dark and never know. So, you keep a running count in your head. Speed, direction, the time that's passed, you stack it up day after day to estimate where you are. Sailors call this dead reckoning, and it's exactly as nerve-racking as it sounds. Every small mistake adds up over thousands of miles. It's even more important in the Pacific Ocean. The distances between islands can be thousands of miles. Get lost and there's nothing to correct against, just water in every direction until food runs out.
Luckily, your instinct is saying you're close. The trouble is, the island is still hidden under the horizon. You can't see it, but other things can. You start to see a lot more birds. Most seabirds sleep on land. They fly out to sea in the morning to hunt, then return to shore every single evening. So, in the late afternoon, you watch the sky. If you see one of those birds flying with a purpose, it's going home. It's pointing at land you can't see yet, but the bird only gets you close.
Now, you need to find the actual island. So, you look at the clouds. Over open water, clouds drift along and mostly look the same, but islands change the air. They heat up differently than the ocean, so clouds often pile up and sit still right over an island, while everything around them keeps moving. A cloud that's parked, when every other cloud is sliding past, is suspicious. There might be land underneath it. And there's another trick. If an island has a shallow lagoon, that water is so vivid that it reflects up onto the underside of the clouds above it. So, the bottom of the cloud glows faintly green. A green cloud in the middle of a blue ocean is land announcing itself on the sky like a sign.
You're basically there, but you still have to actually arrive. Time to use everything at once. The water starts to change color going from deep blue to something paler as the bottom gets shallower. You see leaves floating past, a piece of driftwood, a branch with green still on it, which means it hasn't been at sea very long, which means it didn't come from far. And if the wind is right, you smell it. Land has a smell. Trees, flowers, soil, animals. After weeks of nothing but salt and water, it hits you like a wall.
Remember those swells, the big rolling ones across the ocean? When they hit an island, they don't just stop. They bounce. They wrap around it and reflect back out to sea creating a faint pattern of disturbed water on the far side. An expert navigator could feel those reflected swells in the canoe and know there was an island nearby sitting just out of sight bending the waves around itself. Navigators in the Marshall Islands built stick charts, small frameworks of sticks and shells that mapped how waves curve and collide around islands. But they didn't bring the charts on the voyage. The charts were for studying on land. Out on the water, it all had to be in your head. All of it was memorized and passed down out loud from navigator to navigator for generations.
Humans reached Australia more than 50,000 years ago, which means people were crossing open water long before anyone wrote a single word about it. The Polynesians took it further than anyone. They found and settled nearly every habitable island in the entire Pacific. Hawaii, Easter Island, New Zealand. Tiny specs of land scattered across an ocean that covers a third of the planet. They built double hulled voyaging canoes. Two big hulls lashed together with a deck across the top. Stable and strong enough to carry people, food, water, and animals across the open ocean for weeks at a time.
They did all this at a disadvantage. Sailing east across the Pacific means fighting the prevailing winds and currents, which generally push west. A lot of these voyages were uphill the entire way. Fairly recently, people decided to test it. They built traditional voyaging canoes, learned the old methods, threw away the modern instruments, and sailed across thousands of miles of open Pacific using nothing but nature itself. And they actually made it. It turns out the ocean is quite a reliable guide.
So, let's go back to your canoe. You've been at sea for weeks. You steered by a chain of stars you had to memorize. You felt your way through cloudy nights by the roll of the swells under the floor. You smelled land before you ever saw it. Finally, it lifts over the horizon in front of you. You turn around and look back at the ocean you just crossed. You step onto the shore. No one followed a map to get here because there weren't any. People only drew maps of many Pacific islands after they had already been discovered by navigators who sailed there from memory. You never really knew if another island was out there. You only knew that if you stayed where you were, you'd never find it. Would you have been brave enough to set sail?