They run very small. I am a size 10 and I ordered a 10B(M) US. Turns out, these fit like a 9. I was uncomfortable for most of my cruise as I was counting on these shoes for the hot sand of the beach. My husband ordered the 'mens' version (just changed the colors to blue) and he ordered a 10B(M) US and those fit perfectly. Woman's shoes run small, men's fit like what woman's shoes should be. Lesson learned, don't get cheap shoes.