Fins aren't one-size-fits-all, and the biggest decision isn't the blade — it's how the fin attaches to your foot. Here's the difference between open heel and full foot fins, and which one suits what you're doing.
Open heel fins
Open heel fins have an adjustable strap across the back of the heel — either a traditional buckle or a bungee — and are designed to be worn over a dive boot. That combination gives you more support, better protection from rocks and reef, and enough grip to handle the extra drag of scuba gear. This is the standard setup for scuba diving and for cooler water where a boot is doing double duty keeping your feet warm. The Cressi Reaction EBS Open Heel Fin is a good example of this style.
Full foot fins
Full foot fins have a closed, sock-like foot pocket you wear barefoot or with a thin fin sock. Without a boot and buckle in the way, they're lighter, more streamlined, and give a more direct feel for the water — which is exactly what you want for snorkelling and freediving, where efficiency and comfort over long swims matter more than the extra protection. The Cressi Agua Full Foot Fin is a popular option in this style.
Which one do you need?
If you're scuba diving, get open heel fins and pair them with a proper boot. If you're snorkelling, freediving or spearfishing in warm water, full foot fins are usually the simpler, more comfortable choice. Some spearfishing freedivers still choose open heel for the extra thermal protection and support on long or cold dives — it comes down to the conditions you're in more than a hard rule.
Shop our Scuba Diving Fins, Snorkelling Fins and Spearfishing & Freediving Fins, plus Boots, Gloves and Hoods if you're going the open heel route.