Tagging this as a spoiler just in case, but I personally think this isn’t spoilery.
At any rate, this is one of the highlights of the entire movie in my opinion. There’s plenty of reasons for it being absolutely great as a scene (visuals and the music are two of them), but for me, it’s the way it portrays how the ancient Polynesians crossed the vast expanse of the Pacific to colonise all the many tiny islands scattered across it, often separated by hundreds of miles of ocean without any sort of landmark in sight. That was one of the most amazing things about the Polynesian peoples, and one of the things Western colonisers have tried to erase: that for all the seeming simplicity of their way of life and their technology, they were probably the greatest navigators humanity has ever known.
Imagine trying to navigate the enormity of the Pacific without GPS, or maps, or compasses, or even writing, because the ancient Polynesians had none of those things to help them. Instead, they learned to read ocean currents, weather patterns, the stars, and animal behaviour in order to figure out whether or not they were close to land - but remember that “land” was generally a tiny speck of rock out in the middle of a vast ocean where there was nothing to indicate where you’d been or where you were headed. And then, as if that wasn’t enough, they passed on that knowledge orally, never writing it down. Because of this, it didn’t take very long for colonisation to wipe out enormous chunks of the old knowledge, until what remained had to be pieced together by researchers from oral lore that nearly went extinct. What remains has been portrayed in this scene.
And this is why this movie is important. It’s a reminder to everyone that the Polynesian peoples were not just living hedonistic idyllic lifestyles in grass skirts on gorgeous tropical islands: they were also some of humanity’s greatest explorers. After all, they had to have gotten to those islands somehow, no?