Read the article. Four sentences have been removed from the text. Complete each gap (5.1.–5.4.) with the sentence which fits best and put the appropriate letter (A–E) in each gap. There is one sentence which you do not need to use.

LIVING BENEATH THE WAVES

If there is any place on earth where you can expect to find true believers in the imminent coming of manned undersea outposts or spectacular domed colonies on the ocean floor, it would be here, in Key Largo. 5.1. And it is in Key Largo that you find divers like Ian Koblick, for whom this place is a perfect environment. His even tan hints at his lifetime of outdoor ventures. The wood-paneled walls around Koblick’s office are filled with memorabilia that attest to his years as an undersea pioneer.

For many centuries, the idea of housing human divers on the seabed was unthinkable. 5.2. In order to avoid painful internal injuries and even death, typical dives to modest depths of, say, up to 100 feet lasted only minutes, not the days or weeks that would be necessary to live and work out of a seafloor habitat. But then, a U.S. Navy doctor, George Bond, caused a stir by questioning the conventional diving limits. He and his team started to test the concept known as saturation diving, which turned out to be the key to prolonged underwater stays.

Koblick was among the early converts to the concept of undersea living when it came of age in the 1960s. 5.3. The nascent quest to equip aquanauts to live in “inner space,” as some called the vast undersea realm, never got anything close to the billions of dollars pumped into launching the Apollo astronauts into outer space, but it still turned into a cutting-edge industry.

Koblick may sound like a romantic dreamer for his enduring belief in the value of seabed habitats and his persistent efforts, over many years, to create new ones. But he is not alone. 5.4. They work out of a pair of canal front houses whose interiors have been transformed over the years into mission control for the world’s only surviving full-fledged sea base, called Aquarius. The base has spent more than two decades perched out on a reef 60 feet below the surface and 9 miles from the shore, serving as a scientific research base in the Florida Keys National Marine Sanctuary. The combined activities of this public, science-oriented habitat and Koblick’s private Undersea Park make Key Largo a destination where aquatic dreams live on.

adapted from http://discovermagazine.com