20,000 Leagues Under the Sea : DEEP ATLANTIC: Life, Death, and Exploration in the Abyss By Richard Ellis; Alfred A. Knopf: 396 pp., $35

At the start,” Richard Ellis writes in the preface to “Deep Atlantic,” “this book was supposed to be about an entire ocean.” After trying to integrate material on everything from Scotland’s sea birds to the tides in the Bay of Fundy--and producing a book on sea monsters along the way--Ellis narrowed “Deep Atlantic’s” focus to a combination history of human forays into the deep sea, guided tour of the Atlantic’s nethermost recesses and natural history of the strange menageries that inhabit them.

The “Exploration” section begins with efforts simply to locate the ocean floor, including the British Royal Navy’s successfully using a weighted line to sound the benthos between Norway and Iceland at 4,098 feet and the bewilderment of others who--not realizing their lines were dragging in currents--still hadn’t hit bottom at 50,000 feet. Ellis then treats arguments over the character of the sea floor, such as French naturalist Francois Peron’s theory that the ocean floor was eternal ice, speculation that benthic water compression would keep sunken ships suspended above the ocean floor and--my personal favorite--German biologist Ernst Haeckel’s notion that the bottom of the ocean was made up of a vast, connected sheet of a primordial ooze-midway between life and nonlife that Haeckel delightfully dubbed Urschleim.

Ellis’ history of submarine technology recounts Alexander the Great’s having himself lowered into the sea in a glass-walled box, a submarine-borne orchestra playing the Russian national anthem for a tsar’s coronation and the disastrous early history of military submarines, exemplified by the fate of the Confederate Navy’s Hunley in the American Civil War.

Powered by an eight-man crankshaft, the Hunley had the peculiar weakness (for a submarine) of requiring that its hatch be kept open for ventilation. During trials, it sank four times, killing 23 men. Rather than waste more sailors on tests, a battle crew was enticed aboard with rewards “amounting to several hundred thousand dollars in today’s money,” a certain Lt. George Dixon of the Alabama Light Infantry was directed to steer while looking out the forward hatch and, in February 1864, the Hunley crossed Charleston Harbor, rammed the Union sloop Housatonic and promptly sank both vessels.

A charter member of the International Society of Cryptozoology (devoted to the search for as-yet-unidentified life-forms), Ellis gives the book’s second part, “Creatures of the Abyss,” to a “sunless world” in which “miniature monsters chase and are chased by diminutive dragons; fishes flash, sea cucumbers light up and giant squid, with eyes as big as dinner plates, lurk at the fringes of our consciousness.” He describes oddities like ghost sharks, “flapjack devilfish,” Vampyroteuthis infernalis (the “vampire squid from hell”), rumored 200-foot octopuses and the fascinating ecology of benthic hydrothermal vents--places where lava-heated seawater (up to 167 degrees) supports “gigantic tube worms with vivid red gills emerging from thick, ghostly white tubes that were as much as 10 feet long . . . blind white crabs, pink fishes that resembled no known species and clams that were as big as footballs.”

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Ellis can also be quite wry: In one of the countless footnotes, he describes DOGGIE (Deep Ocean Geological and Geophysical Instrumented Explorer) and DOLPHIN (Deep Ocean Long Path Hydrographic Instrumentation) “as two robotic vehicles whose acronyms must have taken almost as much time to create as the vehicles themselves.” Overall, however, the book’s tone remains one of enthusiastic awe for a world Ellis sees as “the last frontier on Earth.” He insists at one point that “we know more about the back side of the moon than we do about the bottom of the ocean” and then stretches the comparison another zillion years by adding that the deep sea is “as foreign to our understanding as another universe.”

Other universes aside, Ellis’s generally lucid and engaging prose does offer a fine primer on the history and life of the Atlantic, good riffs on plate tectonics and deep sea biology and even an introduction to Latin and Greek nomenclature. The book benefits further from genuinely beautiful illustrations by the author, an accomplished artist who has shown paintings of marine life in galleries and museums around the world. Like Ellis’ prior work on sharks and sea monsters, “Deep Atlantic” comes as close to good pot-boiling as a non-narrative marine science book possibly could, as its author brings to bear a scientist’s knack for detail, an explorer’s capacious experience and a writer’s instinct for the truly curious.