No. Swim diapers only contain the poop and sometimes they don't even contain the babies/toddlers poop very good.
The reason the swim diapers don't swell up like regular disposable baby diapers is because they don't contain the sap "Super Absorbent Polymer" which is what regular disposable diapers use to absorb the urine.
The swim diapers are meant to just contain the poop and not the pee so the pee still gets into the swimming pool.