“I would not recommend the swim line. I love the underwear but this was sub par. As I swam the shorts constantly rolled up and looked diaper esque by the time I got out of the water. The waistband was too large but the hips fit nicely. I often swim with a Mermaid tail, and it fit horribly with the tail.”
“In short: the colors fit differently. There are two waistbands: old style (Narwhal, Rainbow, etc) and a new style (Jelly, Black, etc.). The old waistband has a lot of give, and the new one has basically no give at all. The old waistband will size like their undies, but the new ones you almost definitely need to size up.
I originally bought a Small in the Neon Narwhal print last year. I loved it! For me (5'5.5" 138lbs), the medium also fit, but like it might get too loose when swimming, whereas the small was perfect.
This year, I saw the new Don't Be Jelly print and had to order a pair! I got a small again, of course... but unfortunately the new waistband has almost not stretch at all. Trying to pull it over my hips felt like the stitching needed to rip in order for them to fit! They were much, much smaller. I'm going to exchange them for a medium and hope for the best.”