Nightfall didn't interrupt my observations. I was left to myself. Conseil had repaired to his cabin. The Nautilus slowed down, hovering above the muddled masses on the seafloor, sometimes grazing them as if wanting to come to rest, sometimes rising unpredictably to the surface of the waves. Then I glimpsed a few bright constellations through the crystal waters, specifically five or six of those zodiacal stars trailing from the tail end of Orion.

I would have stayed longer at my window, marveling at these beauties of sea and sky, but the panels closed. Just then the Nautilus had arrived at the perpendicular face of that high wall. How the ship would maneuver I hadn't a guess. I repaired to my stateroom. The Nautilus did not stir. I fell asleep with the firm intention of waking up in just a few hours.

But it was eight o'clock the next day when I returned to the lounge. I stared at the pressure gauge. It told me that the Nautilus was afloat on the surface of the ocean. Furthermore, I heard the sound of footsteps on the platform. Yet there were no rolling movements to indicate the presence of waves undulating above me.

I climbed as far as the hatch. It was open. But instead of the broad daylight I was expecting, I found that I was surrounded by total darkness. Where were we? Had I been mistaken? Was it still night? No! Not one star was twinkling, and nighttime is never so utterly black.

I wasn't sure what to think, when a voice said to me:

"Is that you, professor?"

"Ah, Captain Nemo!" I replied. "Where are we?"

"Underground, professor."

"Underground!" I exclaimed. "And the Nautilus is still floating?"

"It always floats."

"But I don't understand!"

"Wait a little while. Our beacon is about to go on, and if you want some light on the subject, you'll be satisfied."

I set foot on the platform and waited. The darkness was so profound I couldn't see even Captain Nemo. However, looking at the zenith directly overhead, I thought I caught sight of a feeble glimmer, a sort of twilight filtering through a circular hole. Just then the beacon suddenly went on, and its intense brightness made that hazy light vanish.

This stream of electricity dazzled my eyes, and after momentarily shutting them, I looked around. The Nautilus was stationary. It was floating next to an embankment shaped like a wharf. As for the water now buoying the ship, it was a lake completely encircled by an inner wall about two miles in diameter, hence six miles around. Its level--as indicated by the pressure gauge--would be the same as the outside level, because some connection had to exist between this lake and the sea. Slanting inward over their base, these high walls converged to form a vault shaped like an immense upside-down funnel that measured 500 or 600 meters in height. At its summit there gaped the circular opening through which I had detected that faint glimmer, obviously daylight.

Before more carefully examining the interior features of this enormous cavern, and before deciding if it was the work of nature or humankind, I went over to Captain Nemo.

"Where are we?" I said.

"In the very heart of an extinct volcano," the captain answered me, "a volcano whose interior was invaded by the sea after some convulsion in the earth. While you were sleeping, professor, the Nautilus entered this lagoon through a natural channel that opens ten meters below the surface of the ocean. This is our home port, secure, convenient, secret, and sheltered against winds from any direction! Along the coasts of your continents or islands, show me any offshore mooring that can equal this safe refuge for withstanding the fury of hurricanes."

"Indeed," I replied, "here you're in perfect safety, Captain Nemo. Who could reach you in the heart of a volcano? But don't I see an opening at its summit?"

"Yes, its crater, a crater formerly filled with lava, steam, and flames, but which now lets in this life-giving air we're breathing."

"But which volcanic mountain is this?" I asked.