The faster you swim, the faster you get tired. If you use up all your strength then you will slow down. Eat everything you can to keep up your strength and regain health.
You are the Mad Shark. And you're out for revenge against SCUBA-diving scientists who have performed cruel experiments on you.
Even so, your PSP is not a brick. You can easily turn it into one, however, by failing to treat it with care. It's a little too big to be a paperweight, but it would make a fantastic doorstop, as you'd expect at its high price. If you want a doorstop, go to the hardware store and buy one. If you want your PSP to work as a PSP, treat it with respect.