"They conceal information like that in books."

"They conceal information like that in books."
Remember that line from the movie Lake Placid, when someone asks how a crocodile could swim across the ocean? Well, that was in Maine, so no crocodile has (or would) swim there. But we now know the biggest crocodiles in the world swim long distances, and they are smart enough (ok, instinctive enough) to use the ocean currents.  
Saltwater crocs (which can be monsters: a big one may weigh a metric ton)  are spread over many islands of the southeastern (or southwestern, if you're looking from the United States and want to put it that way) Pacific ocean, plus the coasts of Australia, India, Malaysia, etc. They are, surprisingly, not great swimmers. But they have endurance: they can devote weeks to a sea voyage, according to satellite tracking,chomping fish or turtles along the way. One that ventured out to sea from Australia's Kennedy River stayed in the ocean for 25 days and traveled 590km, thanks to a boost from the currents. 
So that's how they swim across the ocean.