There's no real way to do that... why don't you like tampons?
I would just avoid going swimming when you have your period then...
I don't really like tampons either but I still use them. If you don't like the kind you have, try different ones. all tampons fit everyone differently. if you don't won't to buy a whole box you can order samples from feminine products online. I hope this helps and good luck this summer!
I'm a swimmer before. So having my period does not really stop me from training because it's a MUST especially when competitions are coming up. I never use anything. Your period naturally stops in the water, but the thing is once you get out, it flows. I usually just put on the pads/tampons when I'm out of the water. I hope this helps.
Well you could use a diva cup, but you would still have to insert it into your vagina. Otherwise you can't go swimming.