Renowned zoologist Nigel Marven plunges into the prehistoric deep to face some of the largest and most fearsome sea predators that ever existed – creatures so awesome, they make the great white shark look like a goldfish. Scour the depths of seven different prehistoric seas with Nigel as your guide – and marvel at the computer animation techniques that bring each aquatic world to life. Get up close and personal with creatures like the vicious sea scorpions of 450 million years ago, the armor-plated fish of the Devonian Period and a whale-chomping shark called Megalodon. Finally, wade out into the deadliest sea of all time – "Hell's Aquarium" of the late Cretaceous, an ominous body of prehistoric water that gets its name from its elevated water temperatures and the devilish creatures that call it home.