I bought these water shoes for the aqua classes I am taking so my feet would stop slipping on the bottom of the pool. They are perfect for the water exercises, very lightweight and comfortable.  I wear a size 8 and purchased an 8, they fit as I expected them too.  If you need a water shoe with a better arch, you may want to purchase a water shoe that looks like a regular walking shoe, but for as long as I need them (a couple hours), they are perfect.