>She *hates* a lot of the modern fins. She doesn't like the extra length. <
And as a 57-year-old, I agree with her! I love nothing more than a leisurely bit of snorkelling with the all-rubber full-foot style of fins I wore in the 1960s and 1970s. Many of the manuals of that period have photographs of female scuba divers in wetsuits wearing Cressi Rondines and other relatively short-bladed full-foot fins, so don't force your mother into heelstrap fins if she's not keen! DACOR's full-foot all-rubber Corda fins are still on sale after many decades - see
www.kiefer.com, and there are plenty of similar models around, some costing just $20-$30 from other swimming gear suppliers - just click on the "training equipment" button on their websites.