When we think of ‘the final frontier’ and the last unexplored places we tend to think of outer space. Yet despite covering 70% of the planet, more than 80% of the world’s oceans remain unexplored. In fact, we know more detail about the surface of the Moon than the bottom of the ocean, as for most of history we lacked the technology to penetrate its depths. But this began to change on June 6, 1930, when two men climbed into a tiny 5-foot metal sphere and plunged into the waters off Bermuda, descending to a depth of 800 feet – three times deeper than any human had ever gone before. This crude vehicle, known as the bathysphere, helped launch a new era of ocean exploration and gave humanity its first tantalizing glimpses of Earth’s largest and most mysterious habitat.

The two men behind the Bathysphere could not have been more different. At age 52, William Beebe was one of the most famous naturalists in America. The founding ornithologist at the New York Zoological Society, Beebe was a leading expert on tropical birds, a prolific writer and popularizer of science, and an early advocate of ecology and conservation. He was also a figure from another era, a highly disciplined and moralistic gentleman explorer and naturalist in the Victorian tradition.

By contrast, Otis Barton was nearly twenty years Beebe’s junior, the independently wealthy son of New Hampshire textile mill owners. An often difficult man prone to mood swings, Barton had a restless imagination and dreamed of becoming a globetrotting explorer like William Beebe. As a young man he had built his own diving helmet to explore the waters off New York and spent a year on safari in Africa before finally enrolling in Columbia University’s department of engineering.

Yet in one key respect Beebe and Barton were very alike: they were both outsiders. Despite his impressive accomplishments, Beebe had no formal scientific education, having abandoned a degree at Columbia University in 1897 to work for the Zoological Society. This lack of credentials meant that Beebe often struggled to be taken seriously by the mainstream scientific establishment.

In 1928 Beebe established a research station on Nonsuch Island in Bermuda for studying the ocean environment. However, he soon found his scientific ambitions frustrated by the available technology of the time. The standard technique of dredging – dragging a scoop along the seafloor – didn’t allow sea creatures to be observed in their natural habitat, while contemporary diving suits and submarines were unwieldy and unsuited to scientific research. Beebe realized he would need to build his own custom research submersible, and in an article in the New York Times sketched out a concept for a cylindrical diving chamber fitted with lights and portholes, which could be lowered into the ocean on a cable. But Beebe did not posses the technical know-how to construct such a craft, nor did the Zoological Society have the funds to pay for it.

It was then that Beebe’s scheme came to the attention of Otis Barton, who immediately realized that  a cylindrical chamber would not be strong enough to withstand the immense pressures in the deep ocean. Drawing on his engineering knowledge, Barton instead designed spherical diving chamber he dubbed the Bathysphere, from the Greek bathys, meaning “deep”. He then set upon the difficult task of actually trying to contact Beebe; since publishing his article in the Times, the naturalist had been bombarded with dozens proposals from crackpot inventors seeking to share the limelight. But as luck would have it, the idea of a spherical diving vessel had already been proposed to Beebe a decade earlier by none other than former President and fellow conservationist Teddy Roosevelt. Beebe liked the simplicity of Barton’s design, and the two men quickly hammered out an agreement: Barton would pay for the Bathysphere’s design and construction in return for accompanying Beebe on his dives, while Beebe would hire the ship and all the equipment needed to carry out the expedition.

While to modern eyes Barton’s Bathysphere appears crude, at the time it was a marvel of engineering. The craft took the form of a hollow cast-steel sphere 4.5 feet in diameter with walls 1-inch thick – just large enough for two men to crouch inside. Nothing of this size and complexity had ever been cast in one piece before, so Barton turned to the Watson Stillman Hydraulic Machinery Company in Roselle, New Jersey, who specialized in casting cathedral bells. The finished casting weighed an astonishing five tons and was could withstand the pressures at up to a mile in depth. But Barton soon discovered there wasn’t a crane or winch in Bermuda that could lift such a weight, so this first Bathysphere was melted down and recast to a more reasonable weight of 2.5 tons, with a maximum depth of half a mile.

To allow the divers to see outside, the Bathysphere was fitted with three portholes made of fused quartz – a high-strength glass recently developed by General Electric. Oxygen was supplied from compressed cylinders, while trays of calcium hydroxide absorbed carbon dioxide from the divers’ breath. For illumination a powerful searchlight was mounted behind one of the portholes, while a telephone system allowed communication with the surface. The whole device was lowered into the ocean on special high-strength anti-snag steel cable manufactured by Roebling & Sons, the famous builders of the Brooklyn Bridge.

In 1930, Barton and the finished Bathysphere arrived on Nonsuch Island, where Beebe was ready with the expedition ships – an old Royal Navy barge called the Ready fitted with a crane and towed by the tug Gladisfen. Beebe and Barton made their first dive on May 27, 1930, descending to a shallow depth of 45 feet. After several more manned and unmanned tests, they were finally ready to make their first deep dive on June 6. The pair later admitted to being extremely apprehensive, even arranging a system whereby they would speak into the telephone every five seconds; if they failed to speak, they were to be immediately winched up. The dive turned out to be an eventful one, an electrical fire in the searchlight and a leaking porthole forcing Beebe to halt the descent. Nonetheless, they had reached a depth of 800 feet – tripling the previous diving record.

After making minor adjustments to the Bathysphere, Beebe and Barton made dozens of dives throughout the 1930 season, pushing the craft ever deeper and discovering dozens of bizarre new species. The pair also performed physics experiments such as measure sunlight absorption as well as shallow “contour dives” with the bathysphere suspended under the moving ship to map the ocean floor.

While the work was productive, it could also be uncomfortable and sometimes dangerous. Beebe and Barton were both over six feet tall and struggled to cram themselves into the tiny bathysphere, often emerging bruised and bloody from being knocked about inside. At depth the sphere would become uncomfortably cold, and in all but the calmest seas it tended to bounce wildly on the end of its cable, rendering its occupants violently seasick. Worse still, if the Ready sank or the cable snapped, there was no chance of rescue – the divers would plunge helplessly into the abyss. And the consequences of even a minor leak were made graphically clear during one unmanned test dive, when the Bathysphere emerged from the ocean full of water. Realizing this water was under immense pressure, Beebe ordered the crew to stand clear while he started to loosen the hatch bolts. He described what happened next in his bestselling book Half Mile Down:

“Suddenly, without the slightest warning, the bolt was torn from our hands, and the mass of heavy metal shot across the deck like the shell from a gun. The trajectory was almost straight, and the brass bolt hurtled into the steel winch thirty feet away across the deck and sheared a half-inch [13 mm] notch gouged out by the harder metal. This was followed by a solid cylinder of water, which slackened after a while into a cataract, pouring out the hole in the door, some air mingled with the water, looking like hot steam, instead of compressed air shooting through ice-cold water.”

Later, Beebe would somewhat grimly remark that if the bathysphere were to spring a leak at depth, the divers would not have time to drown, for under the immense pressure:

“…the first few drops of water would have shot through flesh and bone like steel bullets.”

Despite this promising beginning, no dives were conducted during the 1931 season due to cracks in the Ready’s winch and bad weather in Bermuda. The ongoing Great Depression had also made expedition funds harder to come by, so Beebe and Barton went in search of a new sponsor. Eventually they secured a deal with David Sarnoff of NBC to broadcast one of their dives live over the radio. To further hype up the event, Beebe and Barton promised to descend to a depth of 2,600 feet – a half-mile down. The dive took place on September 22, 1932, but unfortunately the broadcast didn’t go quite as planned. A rough sea caused Barton to become seasick and vomit, and the moment the broadcast ended Beebe aborted the dive and ordered the bathysphere winched up from 2,200 ft – just 400 feet short of their half-mile goal. But the broadcast had done its job: Beebe and Barton were now international celebrities, their dives seen as death-defying and heroic as the moon landings forty years later.

The 1933 season saw no dives due to lack of funds, with Beebe once more embarking on the fundraising circuit. But money wasn’t the only problem plaguing the project; by now Beebe and Barton’s relationship had become incredibly strained. Their partnership had always been one of convenience, Beebe having the clout and connections to organize the expeditions and Barton the technical know-how to make the Bathysphere work. But despite Beebe’s attempts to give Barton his fair share of credit, the media roundly ignored him in favour of the already more famous Beebe. For his part, Beebe couldn’t stand Barton’s mercurial temperament, indiscipline, and disregard for the natural environment. But there was to be one last moment of triumph. Beebe struck a deal with the National Geographic Society to fund another season of dives in exchange for articles written by Beebe for the Society’s magazine, and on August 15, 1934, Beebe and Barton climbed once more into the Bathysphere and descended to an astonishing depth of 3,028 ft – a half mile down.

The 1934 diving season would be the Bathysphere’s last. Not only had the Depression made the dives too expensive to sustain, but Beebe had seen everything he wanted to see. He and Barton, now on worse terms than ever, parted ways and reportedly never spoke again. William Beebe never returned to the ocean, moving instead to South America and then Trinidad to study insects and rain forest ecology. He would continue to publish papers and books until his death from Pneumonia in 1962. Otis Barton, on the other hand, would spend the rest of his life trying to escape Beebe’s shadow. In 1938 he produced and starred in Titans of the Deep, a half-documentary, half horror exploitation film based on the Bathysphere dives. Not only was the film a notorious flop, but its promotion made it seem as though Beebe was somehow involved in the production, overshadowing Barton in his own film. But Barton did manage to win some of the glory he so desperately sought when in 1949 he rode an improved version of the Bathysphere called the Benthoscope to a depth of 4,500 feet – a record for cable-lowered submersibles that still stands to this day.

Beebe was widely criticized by the scientific establishment for his published work on the Bathysphere dives, particularly for describing four new species of fish based only on fleeting observations through the bathysphere portholes rather than physical specimens. But the true legacy of the Bathysphere was in how it inspired future generations of deep-ocean explorers and launched a new era of scientific research. And Beebe’s tireless promotion of science to the general public would set the template for the science popularizers of the television age, including Jacques Cousteau and David Attenborough.

As for the Bathysphere itself, after its final dive Beebe donated it to the New York Zoological Society, who displayed it in their exhibit at the 1939 New York World’s Fair. It was then placed in the society’s storage yard beneath Coney Island’s Cyclone roller coaster, where it sat, forgotten and rusting, for almost 60 years. Then, in 2005, the Bathysphere was restored to its original condition and placed on permanent display outside the New York Aquarium where it can still be seen today – a fascinating reminder of a heroic age of ocean exploration.

*Note: the name Beebe is pronounced “Bee-Bee”

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