The Deep Sea is a fun little web toy where you scroll down into the ocean to see the depths at which different animals (and a few plants) hang out. Warning: if you start scrolling you probably won't be able to stop until (spoiler alert!) you reach the bottom of the Challenger Deep.

I was surprised to learn many things along the way, including that elephant seals can dive to 2400 meters (about a mile and a half), there's such a thing called the headless chicken fish, the Cuvier's beaked whale is the deepest diving mammal (~1.8 miles), and that "more people have been to the Moon than the Hadal zone" (past 20,000 feet deep).