Period At The Beach!!! :(?

SOOOO I'm going to the beach for the first time ever in my life in two days but I started my period yesterday and it's pretty heavy. I've worn Tampons once before but I didn't put it in far enough so it was really uncomfortable and when I took it out it hurt really bad even though it was NOT dry!!! So I don't really know what to do. Will taking a tampon out hurt as much this time as it did last time??? And is it true that the blood stops flowing when you get in the water??? Soo I don't really know what to do. I'm 13 if that helps. Thanks!!! :)