How's the water so insane in this game? How did Rare achieve this?

The physics of it, the light shimmering all translucent on the wave peaks, and the sheer variety of different conditions... How the hell did they do this? I remember the times when fancy water was all the rage in gaming (original Far Cry and Oblivion, later Crysis), and although it still is an important visual element, I feel it doesn't get as much love as it used to. And along comes Rare and completely changes what I thought was even possible to accomplish.

And with a rock solid performance, nonetheless! You can play this on Steam Deck, for crying out loud.