What would you do if you were me?

Go to the pool and take tampons/pads with you.

It's unlikely your period would just so happen to start while you're in the pool, let alone heavy enough to be noticed - periods normally start light, and thus what little could come out of your body will be diluted so go unnoticed.

If concerned avoid a white bathing suit and have a towel ready when you get out the water, keep checking in the bathroom and if your period does start use a tampon (but remember tampons shouldn't be used before your period or with light flow due to discomfort and TSS risk) or pop on a pad and avoid the pool - either pop on some shorts or a wrap to hide the wings, or opt for pads without wings. You could go get a menstrual cup or softcup on the way to the pool as they can be worn before your period. Also have friends on leak-watch to let you know discreetly.

Go ahead and put a light-absorbency tampon in.

You normally shouldn't use them on any regular basis unless you are on your period.

But this once it's fine.

I'm over 40, have done it occasionally, and never had a problem. Just remember to remove it when you get home.

Put a tampon in your purse or in the bag you carry your bathing suit in, and take it to the pool with you in case you need it.

I would wear a pad, go swimming, get out and change.

(Been swimming with pads on my period for 35 years, no trouble here.)

I'd go to the pool and check for my period every time I go to the toilet.

than just go swimming and you'll be fine

Don't go in the pool.

Go with your fingers (and legs) crossed.

I would just go. if it comes, just use the tampon that I brought along.

Put in the least absorbant tampon you have