Stress
Meets can get pretty chaotic. The pool is crowded with lots of other divers and coaches, and the area is filled with righteous judges along with dozens of admiring fans. Don't forget to take note of where the registration and scoring tables are—they're two of the most important elements of the meet (source). You can't compete if you're not registered, after all.
There's also a lot of pressure that comes with standing alone, above a huge crowd, on a diving board, knowing you're being critiqued. Most people don't like wearing bathing suits anywhere, let alone in front of your peers and total strangers. But hey, it's not like you have anything to be self-conscious about.
There are usually around five scheduled practices a week that can last upwards of two hours each. There's constant variation with the type of training focused on, ranging from strength and flexibility to learning proper dive technique (source). That's not including the additional weight training and stretching you have to do to stay in proper athletic shape.
Even when you're not in the gym, at practice, or in the pool, the burden that comes with being a college diver sticks with you. You need to pay attention to proper nutrition, getting enough rest, and getting used to the coaches, judges, teammates, and professors all expecting more out of you (source).
It's definitely not easy, but it's not exactly rocket science either. Unless that's your major, in which case….well, we hope you knew what you were getting yourself into.