The pool is too cold for your child. Purple lips is a sign of cyanosis - lack of oxygen rich blood. If you want to allow him to swim, try a heated swimming pool instead.
He is probably cold. My niece does have that when she is in the pool for too long, so my cousin would hydrate her with coconut water when this happens
He’s probably too cold so you might want to bring him to a heated pool instead.
May not be anything serious but best to bring your son to the pediatrician...
Is it because your child is cold?
Tan Shi Ying