Nervous about swimming on period!

So tomorrow I'm supposed to go swimming with some students that have some learning disorders and the other volunteers. I'm really nervous cause I'll be on my period and I've never swam like that before! I'm going to wear a super flow tampon, navy blue bottoms with navy shorts on top and then a longer black shirt over my top so that it hopefully covers my butt a bit too. Has anyone had any bad experiences with this? It freaks me out! 😖😶