I bought these for my 91 year old father to wear in the pool during his physical therapy workouts.  The bottom of the pool is quite rough and was hurting his feet.  After much research, I chose these shoes because of the zipper opening.  My father's left foot is always swollen, and some shoes can be difficult to put on, but these slide on quite easily.  They have made his workouts pain free, at least regarding his feet!  Plus, the non-skid bottom keeps him from slipping when he is walking to and from the pool.