Snorkeling fins aren’t just flippers on the end of your feet. You have choices there, too. You can opt for full foot fins or open heel fins depending on what's most comfortable for you.
Full foot fins: These fins are best in places where the water is always warm and typically when you are snorkeling from a boat. You can slip them on, just like a water shoe, and jump in the water—ready to snorkel and explore.
Open heel fins: These snorkel fins are designed for multiple environments. To use them, you’ll also need to buy neoprene booties that fit into the fin’s foot pocket. They are good for different conditions where the water may not always be as warm or when you may have to walk across rocks to the get to the water.
Whichever style of snorkel fin you choose, you’ll want to get snorkeling fins that fit properly. Full foot fins usually run by shoe size, and open heel fins will run XS-XL, with the neoprene bootie matching your shoe size.