The HP is a full-foot model with a slightly longer blade than most other fins. The blade features two flexible channels that allow the fin to alter shape and cup the water on the downstroke to improve thrust. I have a pair for pool use, but was frankly sceptical that such a seemingly lightweight and flexible fin would really cut it in open water. On a trip to the Red Sea I decided to give them a try. I was on a photographic trip, using twin cylinders and also carrying two underwater camera housings. It’s a combination that will create drag however much you try to streamline your equipment.

The Avantis performed surprisingly well. Using them is quite deceptive because the lack of resistance as they cut through the water fools you that you are not really moving. When we hit a current on Ras Mohammed, the Avantis punched through it. For snorkelling, the HP fins get you down and back up swiftly and with little effort, giving you more time underwater. And even two-hour-plus dives produced no cramps or blisters.

Full-foot fins like the HP are ideally suited to boat diving. For shore diving, hard-soled boots are usually essential for protection, making open-heel fins more appropriate. The price ranges from £23.95 up to £35.50, depending on the foot size.

• Phone Blandford Sub-Aqua on 01923 801572.