Setting her tone with the opening header “Weirdness All the Way Down,” marine biologist Scales highlights a select menagerie of strange-looking ocean fauna, from giant and colossal squid (which are actually different species) to bubblegum corals, E.T. sponges, and jellies called “larvaceans” enveloped in floating “snot palaces.” Beginning at the bottom, where in places the mud can run six miles thick, she works her way upward to an open “world with no edges” and finally to the nighttime surface, where trillions of copepods and related creatures serve as “climate champions” by drawing carbon dioxide out of the atmosphere. Oceans contain more than 90% of our planet’s entire biosphere, she notes, and just to demonstrate how much remains to be explored and discovered, she closes with introductions to seven marine denizens first seen as recently as 2022. Taking her cue from a claim that three-quarters of all deep-sea creatures are bioluminescent, Miminoshvili’s wildlife portraits glow in every scene—so brightly that reflections often give skin surfaces a plastic sheen. Still, “weirdness” definitely comes through in full finny, toothy, writhing intensity, while glimpses of the submersibles and remotely operated vehicles that researchers employ and cutaway views of hydrothermal vents add helpful background detail.