“I’d hardly call this shore,” the Canadian replied. “And besides, we aren’t on it but under it.”

A sandy beach unfolded before us, measuring 500 feet at its widest point between the waters of the lake and the foot of the mountain’s walls. Via this strand you could easily circle the lake. But the base of these high walls consisted of broken soil over which there lay picturesque piles of volcanic blocks and enormous pumice stones. All these crumbling masses were covered with an enamel polished by the action of underground fires, and they glistened under the stream of electric light from our beacon. Stirred up by our footsteps, the mica-rich dust on this beach flew into the air like a cloud of sparks.

The ground rose appreciably as it moved away from the sand flats by the waves, and we soon arrived at some long, winding gradients, genuinely steep paths that allowed us to climb little by little; but we had to tread cautiously in the midst of pudding stones that weren’t cemented together, and our feet kept skidding on glassy trachyte, made of feldspar and quartz crystals.

The volcanic nature of this enormous pit was apparent all around us. I ventured to comment on it to my companions.

“Can you picture,” I asked them, “what this funnel must have been like when it was filled with boiling lava, and the level of that incandescent liquid rose right to the mountain’s mouth, like cast iron up the insides of a furnace?”

“I can picture it perfectly,” Conseil replied. “But will master tell me why this huge smelter suspended operations, and how it is that an oven was replaced by the tranquil waters of a lake?”

“In all likelihood, Conseil, because some convulsion created an opening below the surface of the ocean, the opening that serves as a passageway for the Nautilus. Then the waters of the Atlantic rushed inside the mountain. There ensued a dreadful struggle between the elements of fire and water, a struggle ending in King Neptune’s favor. But many centuries have passed since then, and this submerged volcano has changed into a peaceful cavern.”

“That’s fine,” Ned Land answered. “I accept the explanation, but in our personal interests, I’m sorry this opening the professor mentions wasn’t made above sea level.”

“But Ned my friend,” Conseil answered, “if it weren’t an underwater passageway, the Nautilus couldn’t enter it!”

“And I might add, Mr. Land,” I said, “that the waters wouldn’t have rushed under the mountain, and the volcano would still be a volcano. So you have nothing to be sorry about.”