The Diving Fins
Fins allow you to swim and move more efficiently through water while using only your leg muscles. Snorkel fins also provide some floatation for your feet which helps to keep your body horizontal on the surface.
You can choose between full foot fins or open heel fins which are considered to be more comfortable and usually more powerful.

Depending on your preferences you can custom choose each piece from your snorkel set that suits your needs but keep in mind that a perfect experience underwater depends on your snorkel gear.