Introduction -- Beneath the surface / Janet Mann and Andrew Read -- The cetacean brain / Camilla Butti and Patrick R. Hof -- Cetacean cognition / Harley -- Cetacean communication / Laela Sayigh and Vincent M. Janik -- Quintessentially social cetaceans / Janet Mann -- Deep culture / Luke Rendell and Hal Whitehead -- Cetacean tool use / Eric Patterson and Janet Mann -- Us & them / Andrew Read