If i want to write "they are able to go swimming.." is it "ils peuvent se baigner.."? I don't know if I'm meant to use the infinitive of swimming or not! C'est pour un essai du roman "L'etranger" et les relations entre Meursault et Marie.
"ils peuvent se baigner" is good french but vague/general.
It could be "they are allowed to go swimming" or "they are able to".
If you want to convey the idea of beeing able to you have to say :
"ils sont capables d'aller nager".