The "sand shoe" or simply plimsoll is a type of athletic shoe with a canvas upper and rubber sole. It is required whenever someone may have a chance of going aboard a boat as a guest. Like the contemporary Sperry "Top-Sider" shoe, the sand shoe would prevent damage to a boat's deck, and may prevent slipping on a wet surface.
- After the shipwreck, John puts his sand-shoes on the middle thwart to dry (SD7).
- Dot and Nancy both put on their sandshoes when they get up (PM7,18).
- Sammy compares footprints and decides that it is Peggys footprint not Dots: .. jolly lucky we all wear the same sort of sandshoes with a criss-cross pattern on the soles (PM21).
- Roger hears the hobnailed boots of Squashy Hat on the road and recalls that All the Swallows and Amazons had rubber soles, because, as John had said when he was smaller than Roger was now, "You never know when you may get a chance of going aboard somebody's boat." Rubber soles were good for scouting too (PP12).