I normally wear a 10 1/2. I ordered the 11 since many said they run small. The 11 was somewhat larger. I exchanged it for the 10 1/2, its somewhat small, but better than the 11.<br /><br />I wear these on my boat, they stick to wet surfaces great. No black marking either.<br /><br />I wear these on the beach, sand will accumulate in them, but hey it's a sandal, not a flip-flop.<br /><br />One improvement would be for the back strap to be adjustable. When my feet are wet, its a little difficult getting these on. An adjustable back-strap would be good.