“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. “It’s one of the many islets with which this sea is strewn. For ships a mere reef, for us an immense cavern. I discovered it by chance, and chance served me well.” “But couldn’t someone enter through the mouth of its crater?” “No more than I could exit through it. You can climb about 100 feet up the inner base of this mountain, but then the walls overhang, they lean too far in to be scaled.” “I can see, captain, that nature is your obedient servant, any time or any place. You’re safe on this lake, and nobody else can visit its waters. But what’s the purpose of this refuge? The Nautilus doesn’t need a harbor.” “No, professor, but it needs electricity to run, batteries to generate its electricity, sodium to feed its batteries, coal to make its sodium, and coalfields from which to dig its coal. Now then, right at this spot the sea covers entire forests that sank underwater in prehistoric times; today, turned to stone, transformed into carbon fuel, they offer me inexhaustible coal mines.” “So, captain, your men practice the trade of miners here?” “Precisely. These mines extend under the waves like the coalfields at Newcastle. Here, dressed in diving suits, pick and mattock in hand, my men go out and dig this carbon fuel for which I don’t need a single mine on land. When I burn this combustible to produce sodium, the smoke escaping from the mountain’s crater gives it the appearance of a still-active volcano.” “And will we see your companions at work?” “No, at least not this time, because I’m eager to continue our underwater tour of the world. Accordingly, I’ll rest content with drawing on my reserve stock of sodium. We’ll stay here long enough to load it on board, in other words, a single workday, then we’ll resume our voyage. So, Professor Aronnax, if you’d like to explore this cavern and circle its lagoon, seize the day.” I thanked the captain and went to look for my two companions, who hadn’t yet left their cabin. I invited them to follow me, not telling them where we were.