Can I wear a pad while swimming?

Okay so we are going on a cruise after tomorrow and I got my period today. -.- (It'll probably be lighter by the third day, though) I don't wear tampons and my mom won't let me so that is not even a choice. Can I wear a pad? I have done it once when I went to swimming class because the swim coach said it would be fine...and it was. It didn't float up or anything :P Also, I wear shorts over my bathing suit bottoms ANYWAY, so that will help making it not obvious, right? Does the pressure of the water stop the bleeding? For how long? Okay I know that's a lotta questions, hah, sorry. So yeah, please help! Any advice will be greatly appreciated!