I never did much swimming after the age when my breast size became an issue, so it was only relatively recent that I realized my old swimsuit really wasn't holding up! It was a size 14, and designed to fit a C cup. I'm a size 10-12 and a 30F. As you can imagine, every time I came above the water I had to make sure I hadn't fallen out of it! I have since bought a wonderful swimsuit from Panache, which has built in underwire cups. To my surprise, it even fits over my disproportionately large bum.