My daughter is complaining that her ear is hurting. we've spent the past few days swimming in both pools and the ocean. could it be an infection?

Ear infection: Your daughter may or may not have an ear infection. The best way to find out is for her to be seen and examined by her pediatrician or PCP.

Yes: If you tug on the outer ear & that movement causes pain she likely has swimmers ear & needs treatment.If the pain is deeper & unchanged by a little tug of the ear, it is likely middle ear fluid or an infection & may need treatment.In short, it should be seen to know for sure.