Todomomo

Yes, Endeavor didn't want to risk his masterpiece dying from drowning.

Momo's parents took the time to teach her how to swim themselves.

Kirimina

Mina can't, she stays in the shallow end of the school pool. Momo tried to teach her how to but she complains and refuses to learn.

Kiri can definitely swim.

Miruhawks

Rumi? Lmao no, she hates it because of how long her hair takes to dry, and her ears get heavy. Oh and her tail- she hates swimming so she never bothered to learn. Showers and baths are the only time she'll get her entire body wet.

Hawks learned but doesn't really like it.

Iidamei

Iida obviously can.

Mei can but never finds time to go swimming.

Kamijirou

They both can swim, Kaminari just gets scared about using his quirk for several reasons.

(Yo so if Manual and Denki teamed up, Manual could put water on the ground, and Denki could electrocute the villains-)

Dabi x Toga

Dabi doesn't, Toga kinda knows but she hasn't done it in a while so all she knows is how to not drown and how to tread. So basically no.

Nejitama

They both know how

Mt.Kamui

Bikini and beach photoshoots may make it look like she knows how, but Yuu will friggen drown

Kamui knows how to swim.

Ryushot

Ryuko will hiss like a Friggen cat if he even tries to put her in a pool without a floaty. She can't swim so she just sits on the side or in a floaty.

Shinya probably knows a bit but not a lot.

HitoRei

I-

REIKO LITERALLY SURFS AS A HOBBY.

Reiko and Hitoshi can swim.

Tetsukendou

Their quirks make it hard to swim.

So no. They can't swim at all.

(Sorry for being inactive for a while, I took a nap.)