What comes to mind when you think of the ocean? Maybe a day at the beach — swimming in the waves, snorkeling through coral reefs, fishing, surfing, and sunsets that kiss the blue horizon. But Earth's oceans are more than all of that; they're our planet's defining feature, its largest ecosystem, the original source of all life, and, according to physicist and oceanographer Helen Czerski, the engine that powers our planet. On this episode, we talk with Czerski about her new book, "The Blue Machine: How the Ocean Works," and why she says the ocean is critical not only to our climate system, but to the big and small processes that sustain and shape life on Earth. She also helps us understand the many intricacies of the sea, from the reasons why it's salty to how the Earth's rotation affects its currents. We also hear stories about efforts to restore coral reefs using sound and find out why scientists are looking for climate time capsules at the bottom of the ocean.