If you look at a map of Earth, it’s mostly water. If you look at a human being, we are mostly… not designed for that. We lack gills, we aren't exactly aerodynamic, and our lungs have very loud opinions about being squished. Yet, for some reason, since the Stone Age, we’ve been looking at the abyss and thinking, 'I should probably get in there.' Today, we’re exploring the history of the deep dive—from cave paintings to the 'martini effect' of nitrogen—and why humans keep trying to negotiate with an environment that doesn't speak our language.