Tubercles. That's the name for the bumpy area on the fins of humpback whales, and it's also the inspiration for the Nemesis Fins from Speedo. Tubercles create surface area for water to pass over, allowing you to push more water and pick up speed when you need it most. And with square openings named blow valves, water is captured and forced through creating more force on downward kicks. And while it has plenty in common with whales, these were made for you, with superior arch support, extra toe space, and a graduated instep for exceptional comfort.