Trip Report: Hall City Cave (2010 Sep 11)


High in the mountains of Northern California is an underwater cave that is rumored to have stolen gold hidden in it's depths. Despite many reported attempts to venture to the cave's end, no one has ever seen how for it goes or what lies inside. Using a home built OpenROV submarine, I intend to teleroboticly explore the parts of this submerged labyrinth that have never been seen by human eyes before.

Here is the story that started it all...

Reconnaissance Expedition

In September of 2010, Bran Sorem, Jeff Bernard, and myself mounted a reconnosance expadition to find and explore the Hall City Cave. Information gathered durring this trip about the Cave's exact location, accesability, depth, and features would help for planning our next trip which would include the (at that point still being designed) OpenROV. We left from Eureka, CA in the early morning of September 11 with plans to drive to the Cave, spend several hours there, and drive back in the same day. Here is the plan we put together:

Jeffrey (Fej) Bernard
Brannen Sorem
Eric Stackpole

0830: Eat hearty breakfast and load up the mid-engined sports van
0845: Eric arrives at Fej’s house
0846: Slap Fej for sleeping in and not being ready to go
0847: Eric gets kicked for obvious reasons
0900: Depart Fej’s house
0930: Pick up Bran in Eureka
Get needed supplies (glow sticks, food, extra batteries, etc)
1145: Arrive at Wildwood
1230: Finally find entrance to cave after Fej stupidly insists that it was in the other direction from where we parked
1630: Exit Cave
1700: Start driving back to the coast
1930: Drop Bran off at his house/ review photos
2030: Drop Fej off at his house


Dress for wet and muddy conditions (may be on hands and knees at some points) and expect jagged rocks. Temperature may be in mid 40’s inside cave.

Personal equipment: (each person should bring their own)
Backup flashlight (headlamp works)
Complete change of clothes
Gloves (for jagged rocks)
At least 1L of water and food

Technical equipment: (Brought by whoever is listed in parenthesise)
Compass (Eric)
Long (>300ft) of string (Fej)
Measuring tape (Fej and Eric)
Chem lights? (We’ll get on the way)
GPS for marking entrance location (Eric)
Cameras (EVERYBODY- bring your arsenal)
Charged/extra batteries
Free/extra memory
Hard / waterproof enclosures for fragile equipment (Everybody bring what they’ve got)
Rope appropriate for ascents/ descents (Eric and Fej)
Notepad and writting utencil for recording map and notes (Everybody)

iPod for drive
Food for drive


As expected, the drive took approximately two and a half hours from Eureka. We entered the small town of Wildwood and drove around for a bit before finding the route to the cave which was a small forest road that wasn't much wider then my van.

Fig 1: Forest Road on the way to the cave. There were even several signs showing us the way at major forks.

Along the way, we ran across some locals who were chainsawing a log that had fallen across the road. We asked them about the cave and they said they knew of it but had never seen it, and that they had also heard the story about the gold but didn't know any more details than what we had already read.

After several miles of driving, we arrived at the end of the forest road and an open graval area where we could park. As we entered the clearing, we noticed a small creek to our left and the beginning of a small trail going along side the creek. To our right was a steep hill with a gated road going up the hill. We decided that we would walk up the hill along the road before exploring elsewhere.

Fig 2: The three of us before starting our exploration. From left to right: myself (Eric Stackpole), Jeff "Fej" Bernard, and Bran Sorem

About a quarter mile up the hill, we came across a square (clearly man-made) tunnel going into the hillside- we found an old mine! The floor of the mine was flooded with a few inches of water, and we could see two very deteriorated wooden tracks (presumably for mining carts) running into the mine which we walked along. The mine went in a straight direction for several hundred feet before branching off to the left where there was a rubble pile. Fej was interested in climbing over the rubble pile and exploring further which did sound very enticing, but we decided that it would be better to use our time to find the Hall City Cave, and come back if we had any time left over.

Fig 3: Looking down mine. Note tracks running along tunnel floor

After spending a few more moments looking around the mine, we made our way out and decided to head back down the hill and walk along the trail running along the creek. One website we found mentioned that the cave could be found by following switchbacks up a hill immediately after crossing a creek, so it seemed likely that this trail would lead us there.

Fig 4: Trail running along side creek on way to Hall City Cave

After only about a quarter mile, the trail crossed the creek and sure enough, there were the swtichbacks we had heard about. We followed the trail up the hill a hundred feet or so before it straigtend out, and in minuets, almost by surprise, we caught site of a granet outcroppoing marked by a vertical wooden post. We had made it to the entrance of the Hall City Cave.

Fig 5: Entrance to the Hall City Cave

The entrance to the cave was narrow and tall, and required a jump down of about 4 feet from the leval of the ground outside the cave. The granet outcroppoing extendted quite a way up the hill and was covered by loosly packed dirt which made it hard to climb. I tried to get a GPS fix on the exact location of the entryway, but for some reason was not able to aquire enough satellites (perhaps due to tree cover). We stowed the equipment we woudn't need in the cave (hiking gear, radios, extra cloths, etc) and climed down into the entrance.

More details about what we found coming soon.. In the mean time, here is a crude sketch of how the cave was laid out. The distance from the entrance of the cave to the water was about 80 feet.

Fig 1. Rough sketch of Hall City Cave layout