While at the bottom, the explorers not only saw jellyfish and shrimp-like creatures, but actually spied a couple of small white flatfish swimming away, proving that at least some vertebrate life could withstand the extremes of the bottom of the ocean. They actually managed to speak with the craft's mothership using a sonar-hydrophone system at a speed of nearly a mile per second, it still took about seven seconds for a voice message to travel from the craft upward. The two men spent just 20 minutes at the ocean floor, eating chocolate bars for energy in the cold deep, the temperature in the cabin was only 45 degrees Fahrenheit (7 degrees Celsius).
As if to highlight the dangers of the dive, after passing about 27,000 feet (9,000 meters) one of the outer window panes cracked, violently shaking the entire vessel. The descent the first and only manned voyage to the bottom of Challenger Deep took 4 hours and 48 minutes at a rate of about a yard (0.9 meters) a second. 'The pressure is tremendous,' said geophysicist David Sandwell at the University of California, San Diego, who helped create the first detailed global maps of the seafloor.
