Nature’s new documentary, “Superfish,” which premieres this Sunday at 8pm, follows marine biologist and filmmaker Rick Rosenthal across three oceans and more than two years on his quest to film the biggest, fastest, most dangerous gamefish in the sea — the ancient and amazing creatures known as billfish.

But the open ocean isn’t the only place to find amazing swimmers. Beneath Death Valley — the hottest, driest place in the Western Hemisphere — stretches a vast aquifer system, within which you’ll find one of the most astounding creatures on Earth: the critically endangered Devil’s Hole pupfish, marooned below the desert floor since the Ice Age.