Once again, Ken offered to take the number two spot. We splashed in the Glory Hole, following our yellow descent line down to the drop weight at the top of the Anthill. There, I looped a cave line around the thicker rope and swam diagonally down the slope, past the derelict outboard motor, and down to the twisted sheet of corrugated metal roofing.
I found the rounded entrance to the Rabbit Hole easily this time, and after exchanging OK signs with Ken, we entered the murky passage. About 50 feet in, I reached a wooden beam supported on each side by timbers. I hadn’t seen this structure before, which meant we’d already progressed further than the point at which I’d turned around on my initial dive. I tucked my arms to my sides and kicked under the wooden support that had been constructed a century earlier to support a section of the ceiling the miners thought might collapse. Comforting thought.
As I moved, I kept my light swinging around the perimeter of the passage, searching for signs of instability or a branch passage that might confuse us on our exit swim. But the dimensions of the tunnel remained a steady four or five feet in width, and about the same distance high. Reddish silt clung to the rocks, and blanketed the floor. Looking back between my fins, I could see Ken’s light a few feet behind me, its glowing orb already diffused by the cloud created by my careful movements.
Twenty feet beyond the timbered support, we reached a spot where the silt on the floor seemed to grow thinner, dropping away into a series of small holes. Looking more closely, I realized the gaps in the silt were caused by rotten timbers that had lined portions of the floor. The boards had broken and separated, and in a few places the gaps appeared wide enough for a streamlined diver to drop through to a chamber below.
I shone my light through one of the larger holes. The beam lit a cavern of indeterminate size, and the water that filled it seemed clear although I knew this was an illusion created by the flecks of silt filling the water on my side of the opening. I circled the hole with my light beam to make sure Ken had seen it, and continued on.
I could form only a rough estimate of how far we’d traveled. By intention, we were moving as slowly as possible in order to minimize our disturbance of the particulate in this cramped, non-flowing passageway. Thrusting my light ahead of me, its powerful beam sweeping the walls and ceiling of a mine tunnel that had not been visited by another human in a hundred years, I could make out only shapes a body-length ahead. Despite its narrow confines, the tunnel seemed to swallow the beam of my light. I clutched the reel in my left hand, glancing at the Hammerhead display strapped to my forearm. The gauge read 72 feet, but I’d never felt deeper. The tide had been high when we went in, which added 10 or 12 feet to the depth when I had made my exploratory solo dive, but the tunnel we’d been following must have descended without us realizing it.
After a few moments, the drift grew almost imperceptibly wider. I hugged the left side as I swam, and little by little the wall that had been just off my right elbow grew farther away. I reached a stout vertical timber, probably 8 or 10 inches square, which protruded through the silt on the floor and disappeared into the haze over my head. I groped with my light, and could see other timbers set at regular intervals ahead. There may have been thinner boards set as diagonal braces—I couldn’t be sure.
My sketch showing the Rabbit Hole tunnel intersecting the main shaft
The crest of the debris mound outside the tunnel
Five—Into the Unknown
Based on our initial exploration of the two tunnels, Ken and I agreed that the most likely route to the mine’s vertical shaft—and through that, access to the deeper 200-foot level with its network of passages—probably lay through the straight tunnel that I’d partially explored on my solo penetration. We planned a dive that would take us to the end of this passage, and which we hoped would reveal whether the shaft could be reached via this route.
100-year-old log retaining wall inside the flooded mine
I stole a glance at Ken to make sure he was close by, then passed my reel around the massive post and pulled the line taut. When it had tensioned, I took a half-dozen twists around the line and clipped on a line arrow pointing back the way we’d come. We hadn’t found a single tie-off point since we’d passed the first set of timbers near the entrance, and even though our passage had been straight through the tunnel, with no side openings, I felt a sense of relief knowing that we now had a well-secured line that would take us home.
I wanted to make sure that Ken got a good look at the wide area of the tunnel before our suspended silt drifted up and obscured his view. Keeping close to the wooden timber on my left, I reached back with my right hand and motioned Ken to come up alongside. A moment later he was next to me, probing the darkness in front of us with his own light. We could make out a framework of heavy wooden timbers, their dark shapes covered with a thick coating of orange-tiled silt that clung to each vertical surface, and lay dense as cotton on the horizontal ones. Just overhead, a greasy-looking halocline reflected the beams of our lights.
I gave my wing a small burst of air. My head rose above the misty layer, and I could discern a sharp increase in the water clarity. Right at the level of the halocline, the thick orange overburden clinging to the timbers changed noticeably. In the brackish lower level, it coated the timbers and nearby rock walls in thick, mossy tendrils. Above the halocline the growth was still prevalent, but much thinner.
After we’d popped our heads in and out of the halocline a couple of times, Ken and I moved ahead slightly and stabbed the blackness ahead with our lights. Although the upright shapes of the supporting timbers were fairly distinct (despite their thick coating of orange-tinged moss), the enormous drifts of silt on the floor made it difficult to distinguish what the tunnel was doing. There appeared to be a large rectangular hole in the floor, like an open elevator shaft or the cargo hold combing of a sunken steamship. The silt tapered evenly at the edges of this opening, clinging stubbornly to an angle of repose before dropping away into nothingness. Whether the passage we’d been following continued on or dead-ended at the shaft, we could not say.
Rising upwards and peeking above the halocline, I could make out the hazy geometric shapes of the wooden timbers rising toward the surface and what was now the compacted plug of timbers and garbage that had been dumped in when the shaft was sealed from the surface. Looking down, past the mounded silt, we could see that the shaft was open below. We had found what I believe is the access to the deeper levels of the mine, including the gigantic amphitheater created on the 200-foot level when the rich deposit of copper ore was extracted more than a century ago.
But that discovery would have to wait. I don't know how Ken was feeling, but my nerves were thrumming from the tension of cautiously maneuvering through such a malevolent environment. I wanted out!
We checked our tie-off, cut the line, and exited the Rabbit Hole the way we’d come. Despite the care with which we had navigated the passage, our swim out took us through a complete silt-out, the thin white cave line providing our only connection to the outside world.