I should start out saying I wear a size 9 shoe, normally a 9.5 with sneakers.  I also have a narrow foot, so I can't wear most sneakers.  I've had a pair of size 9 Salomon water shoes and finally had to replace them.  I bought a size 9 hoping they would fit, but sadly they were too wide and a tad too long.  These are very nice and I wish I could have kept them.