I went scuba diving for the first time a few hours ago. I'm exhausted and have shortness of breath. No particular pain, just discomfort. Is it normal?

ScubaDubaDooToYou! Well, I don't know where you are right now but wherever it is, make sure you know where the nearest ER is, just in case. You might just be tired or exhausted, depends on how fit you are and how many times you've dived, if you had lessons, how much exertion and especially how deep you went , for how long and what your ascent to surface. If anything worsens better safe than sorry, go to the ER.