Not to name any names, but some people get a little panicky if they inhale at the wrong moment in the shower and end up with a nose full of unexpected water. So imagine the utter terror we — er, they — will experience when immersed in prehistoric oceans infested with predators so awesome they make piranhas look like plankton. Set 80 million years ago, National Geographic’s Sea Monsters does just that, following the life of two Dolichorhynchops (late-Cretaceous plesiosaurs, if that means anything to you) as they navigate the earth’s waters. Even if you wouldn’t know a Dunkleosteus from a Mososaur if it devoured you in a single bite as you bobbed helplessly atop a roiling sea, this new animated feature will probably give you a start. Deep breaths. Deep breaths.