Really? I have always figured that if anything can be rented it is fins. . . .
When InselAir lost, er, delayed, my wife's checked bag enroute to Bonaire, the dive op was able to lend her some fins, but they only had the closed-heel type. (They had open-heel fins for SALE, but not as rental equipment.) So, without her beloved hard-soled dive booties, she found herself having to walk out over the rough ironshore in flip-flops, then switch to the fins. She cut her legs up pretty nicely after falling over. At least for Bonaire, with its notorious shore entries, we will no longer put fins and booties in the checked bag. We have travel-sized fins now that come with us on our carry-ons.