very flexible; however, there should be a softer insole for me - it comes with a rubber sole that doesn't give way but isn't too hard either. I think this is unusual for this type of shoe as they are not intended for use in water. I really like the softness of the top. I usually wear a size 8 but my thumb goes to the bottom of the toe box so I returned it and bought a size 8.5 and it fits better but I have to tie my laces tighter than a size 8 and wear socks that fit on top . upper laces so my skin doesn't chafe when I walk. So maybe order half a size bigger. I think you will still want to wear socks with non-absorbent rubber inserts.