If we were able to listen under water, what would we hear? What would we learn? How would it change us? With erudition and charm, marine scientist Bill François takes us on a deep dive into the secret lives of the world's aquatic creatures, from musical whales and immortal eels to the cod that discovered America and the herring that almost caused a military conflict. A poetic blend of ancient myths, modern science, and storytelling through the ages, this guide to a dreamlike underwater world helps us to hear the songs of seahorses and scallops, eavesdrop on the conversations of lobsters, and swim in the glow of the fluorescent jellyfish.