I think this is going to work for my teen for lifeguarding. However, she is a solid med/6 occasionally 8 with 5'6" 140 athletic build. 1st order was a size 8 and was so small she told me to try a 12. 12 worked. Size up at least two sizes!

So far, so good! I love that is covers everything. I don't have to worry about flashy anyone. It also dries pretty quickly, as soon as I got out of the pool and shower most of the water had drained out. I bought a large. I am 5'10, 170 lbs and wear a size 10-12.