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How do cetacean flippers help them move through water?

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Illustration showing various cetaceans, including baleen whales like the blue whale, fin whale, humpback whale, gray whale, sei whale, northern right whale, and bowhead whale, as well as toothed whales such as the sperm whale, narwhal, beluga, Baird's beaked whale, killer whale, dolphins, and porpoises. Each species is labeled with its scientific name and typical or maximum length, with a size scale in the corner for reference. — cetacean Whales (order Cetacea).

Cetaceans, which are mammals, have evolved from four-legged terrestrial ancestors into aquatic creatures. While their hind limbs have been lost, their forelimbs have been reduced to finlike flippers that serve primarily to steer the animal.1

Unlike some other aquatic animals that use their limbs for propulsion, cetaceans rely on their powerful back muscles to drive their horizontal tail flukes for movement. The flippers function as steering organs and help counteract pitching, or dorsoventral seesawing movements, during swimming.12