Among my favourite mysteries of the natural world is Bathysphaera intacta, a 6ft fish said to resemble a large barracuda. The new species was supposedly spotted by the explorer and naturalist William Beebe in 1932 at a depth of 640 metres (2100 ft) off the coast of Nonsuch Island in the Bermuda archipelago. We have no photograph of the fish and the only image that exists was drawn by Else Bostelmann, a German-born American artist, who accompanied Beebe on his expedition. Bostelmann never descended into the ocean’s depths; her drawings, based on Beebe’s descriptions, are 20th-century marine equivalents of Dürer’s Rhinoceros, creatures that the artist had never seen first-hand.
Fans of Dürer’s woodcut will enjoy Brad Fox’s The Bathysphere Book. It is an alternative history of Beebe’s exploration of the deep ocean, a weird and often beautiful fusion of science writing, history and poetry that explores our own relationship with the unknown – how we make sense of something fundamentally new with the limited tools at our disposal. It’s a story largely set in the Bermuda archipelago in the 1930s, but it somehow seems more ancient than that; Fox’s protagonists resemble literary trespassers into the underworld, frustrated by the limits of human language and anxious that their experiences will be misunderstood or dismissed by those on the surface.
The book takes its name from the vessel in which Beebe and his colleagues descended into the depths of the ocean. It was the stuff of childhood fantasy: a 1.4 metre steel ball tethered by a steel cable which could be winched from a supporting vessel at the water’s surface. This extraordinary invention allowed Beebe to descend beyond 900 metres (3,000 ft), smashing previous records. Peering out of the small quartz windows of the Bathysphere, he observed a previously unknown world: strange and terrifying creatures that could survive vast pressure and lived within a new kind of darkness (“a solid, blue-back world, one which seemed born of a single vibration,” writes Beebe). It was dangerous and claustrophobic; Beebe and his colleagues continually faced the risk of being crushed or asphyxiated, of becoming part of the world which they sought to represent.
The most fascinating passages relate to how members of the expedition sought to bring to light this new world of darkness. On one level this was a technical problem: conditions were so poor that Beebe was unable to rely on photography; instead he would peer out of the Bathysphere and relay by telephone what he saw to Gloria Hollister, the expedition’s scientist, on the supporting vessel (Fox includes excerpts from Hollister’s transcriptions which read like surrealist poems). On another level, the challenge was philosophical: how can you represent a world using tools intended for another realm? Beebe himself grew sceptical about the adequacy of human language, and was often lost for words, repeating “black, black, black” to Hollister. His inarticulacy, he wrote, was the “penalty man must pay for rushing into new dimensions”.
Fox spent years poring over Beebe’s notebooks, and he brings to life the explorer’s boyish curiosity, sensitivity and flaws. Yet the book is not a biography. Fox makes continual dives into human and non-human stories, introducing a range of colourful characters who flash into view and then disappear back into the darkness: artists, scientists, adventurers, local Bermudians, as well as the (sometimes dubious) individuals who backed Beebe. If their fleeting presence sometimes threatens to overwhelm us, his passengers, perhaps feelings of disorientation befit the subject – an encounter with a new, sensual realm.
Fox quotes Kipling, who, having learned of Beebe’s first dives, wrote: “The time will come when we will draw the curtains of the back parlour, turn on the television, and see the wonders of the Tuscarora Deep.” With the arrival of drone technology and modern cameras, that time has arrived; we can now peer into the ocean as if sitting in our own personal Bathysphere. And yet Fox’s book reminds us that, for all the excitement of these technological advances, something has been lost. According to Fox, no one has managed to prove the existence of Bathysphaera intacta; we are still searching for it in the depths, unsure where knowledge ends and imagination begins.
• The Bathysphere Book: Effects of the Luminous Ocean Depths by Brad Fox is published in the UK by Pushkin (£22) and in the US by Astra House. To support the Guardian and Observer, order your copy at guardianbookshop.com. Delivery charges may apply.