Our navigating continued under these conditions until March 13. That day the Nautilus was put to work in some depth-sounding experiments that fascinated me deeply. By then we had fared nearly 13,000 leagues from our starting point in the Pacific high seas. Our position fix placed us in latitude 45 degrees 37′ south and longitude 37 degrees 53′ west. These were the same waterways where Captain Denham, aboard the Herald, payed out 14,000 meters of sounding line without finding bottom. It was here too that Lieutenant Parker, aboard the American frigate Congress, was unable to reach the underwater soil at 15,149 meters. Captain Nemo decided to take his Nautilus down to the lowest depths in order to double-check these different soundings. I got ready to record the results of this experiment. The panels in the lounge opened, and maneuvers began for reaching those strata so prodigiously far removed. It was apparently considered out of the question to dive by filling the ballast tanks. Perhaps they wouldn’t sufficiently increase the Nautilus’s specific gravity. Moreover, in order to come back up, it would be necessary to expel the excess water, and our pumps might not have been strong enough to overcome the outside pressure. Captain Nemo decided to make for the ocean floor by submerging on an appropriately gradual diagonal with the help of his side fins, which were set at a 45 degrees angle to the Nautilus’s waterline. Then the propeller was brought to its maximum speed, and its four blades churned the waves with indescribable violence. Under this powerful thrust the Nautilus’s hull quivered like a resonating chord, and the ship sank steadily under the waters. Stationed in the lounge, the captain and I watched the needle swerving swiftly over the pressure gauge. Soon we had gone below the livable zone where most fish reside. Some of these animals can thrive only at the surface of seas or rivers, but a minority can dwell at fairly great depths. Among the latter I observed a species of dogfish called the cow shark that’s equipped with six respiratory slits, the telescope fish with its enormous eyes, the armored gurnard with gray thoracic fins plus black pectoral fins and a breastplate protected by pale red slabs of bone, then finally the grenadier, living at a depth of 1,200 meters, by that point tolerating a pressure of 120 atmospheres. I asked Captain Nemo if he had observed any fish at more considerable depths. “Fish? Rarely!” he answered me. “But given the current state of marine science, who are we to presume, what do we really know of these depths?”