Several pairs of used water shoes. My kids grew out of these.
pink ones size 13. The pink is a little faded and not as vibrant as they were when new and the soles have some wear but totally usable.
Light blue/grey ones with velcro straps size 5
Blue and black ones boys size 5
White, light blue and royal blue ones are size 6. (They're about identical in size to the above boys 5, so maybe a girls 6?)