I am an adult with a small/medium sized head and thin, shoulder-length hair. This swim cap fits fine - if anything it's a little loose - but it does the job. I use swim caps because my ears get plugged if I swim without one, and although the edges of the cap flip up sometimes it does a good enough job at keeping the water out that I haven't had any problems.If you are looking for a swim cap to protect your hair from getting wet, this did not do the job for me. That being said, I have yet to readSee full review