It feels strange the first time. Your mask, your awkward gear, a bit heavy. You ease into the water and your face slips below the surface. Inhale; the air comes with a reassuring hiss, and for the first time, you breathe underwater. In moments, you forget your mask. Your equipment transforms to light and agile, and you're free like you've never experienced before. With that first underwater breath, the door opens to a different world. Not a world apart, but different nonetheless.

(Introduction to the PADI Open Water Diver Manual)