You can find both types of fins when you're looking for snorkeling flippers. Full-foot fins are usually the better choice when you snorkel in warm water. You wear these types like a shoe and slide them on while you're barefoot. Snorkel fins with open heels work better in cold water. You will usually wear booties with this type. You can use the heel strap to loosen or tighten around your foot making these adjustable fins. They come with the same pros and cons as you have when you look at fins for scuba diving.