Otter Hole Sunday 20/01/18

Members Present: David Botcherby, Louise Baddeley, Helen Fairclough, Jack Dewison, Will Whalley, Adrian Fawcett (HCC)

I believe this trip first formed in the pub about 4 months ago. Someone was telling me about this brilliant cave with a tidal sump that SUSS used to go down once a year, that needed to be booked months in advance. Instantly keen, I wrote a note to self on my hand, and next day found the calendar online, and booked a weekend that was (at the time) free of SUSS activities.

Otter Hole lies on the banks of the river Wye, not far from where it flows into the Severn Estuary. When the tide comes in from the sea, this acts to push water in against the river current, raising the river level. Inside the cave, this diverts the streamway, filling a sump at high tide. This tidal sump is impassable when full, but only waist deep at its lowest. As a result, two kinds of trip are achievable: a between-tide trip, in which the sump is passed just after high tide, and returning before it closes again; and an over-tide trip, in which the sump is passed as it closes, and cannot be repassed for around 6 hours. The over-tide trip allows more time to explore the large cave system, and is way cooler in my opinion with being blocked in by the tide. Luckily the weekend I booked was down as an over-tide trip, so I was pretty keen despite the 4 month wait for the trip.

As is always the case with SUSS, the weekend I thought to be free was quickly earmarked for bolting training. Luckily, this was only for the Saturday, so we planned to drive out to the Forest of Dean as soon as we were done. Bolting training, as it turned out, had a large component of enjoying the sun in a pleasant quarry, so we were all quite relaxed and ready to head off at about 4. With 5 of us in the car it wasn’t the most spacious journey, but the impressive boot size of the Skoda Fabia estate went some way to improve our comfort. We’d chosen to stay the night at the closest (and cheapest) campsite to the cave, so we could drive over quickly in the morning, as we had a 07:15 start. Beeches Farm campsite turned out to be quite pleasant, affording us a beautiful view of the Wye Valley as the sun went down, and provided a fire pit reclaimed from an old tractor wheel. We turned in fairly early considering our early start (and lack of alcohol), but not before seeing (or mostly hearing) some firework displays for the royal wedding across the valley.

We woke at 6am, scrambling out of tents to enjoy a breakfast of peanut butter on bread in the dewy morning. Will’s claim that sleeping in a bivvy bag meant he could be packed in 30 seconds were quickly proved untrue as he was the last to be ready (though a long trip to the toilet block may have been part of this). I drove the 25 mins to the car park as it had no motorways, passing by Chepstow racetrack on the way (which we would later almost visit from underneath). As we approached our destination the vague directions got the better of us, ending in us rolling quite uncertainly into a walker’s parking area. While we were debating whether we were in the right place a caver-looking car rolled in behind us and parked nearby. Hoping that this was our guide, I parked up right next to them and hailed the driver. I was fortunately correct in my assessment, and this was our guide Adrian from the Hades Caving Club.

We kitted up in the car park, making sure to bring food water, and spare batteries for the long trip. Adrian was very friendly, only berating us for choosing a trip with such an early start. The walk to the entrance quickly became very sweaty in the morning sun, even with the shade of the trees. Even so, it was very pleasant to be walking in the Forest of Dean, with the river visible through the trees. At the entrance, we made a very interesting discovery of a bank of Bird’s Nest Orchids. These rare white orchids lack chlorophyll, and live parasitically on their fungal mycorrhizal partners, indirectly drawing organic photosynthates from the nearby trees through a shared mycorrhizal network. For the three biologists on the trip this was very exciting, although the others didn’t seem to be quite so enthused, Adrian almost sitting on one as he filled in the logbook. Unfortunately, we didn’t get a picture, as we’d left our phones in the car, but there was a whole bank of them, right outside the cave entrance!

A picture of a Bird’s Nest Orchid I nicked from the internet

The entrance series is very Derbyshire-esque, with tighter sections giving way to mud slogging and sliding. This was quite fun, with a few unique moments, such as the ‘pyramid step’, which involved positioning your person across a pit to perch on the point of a pyramidal protrusion. As we approached the tidal sump, the mud took on a silty river bed quality, and became quite a slog to move through. The sump was near its lowest point, and so was only waist deep, but provided some much needed cooling after our previous exertions. As we passed through I looked up at an eyehole squeeze in the ceiling, with a rope rigged underneath. Adrian explained this was for a tightrope style traverse across the top, which seemed quite unbelievable, but I would later be shown this was not quite as unlikely as it appeared.

After this point, the cave becomes mostly stomping streamway. We made good pace through this, hopping over various climbs and traverses. We reached a junction with some brushes to wash ourselves down, as this was the last wet point before the pretties. Despite Adrian’s warnings of the futility of washing ourselves too thoroughly, we all gave it a good go, mostly to cool down. We had a quick gander at the downstream sump, where Jack undid his oversuit to ‘inspect the streamway more thoroughly’. The way on was at the brush junction, where the connection to the rest of the cave is found. Otter Hole is actually composed of an active streamway section, which we had just traversed, and a much larger fossil system, which was reached though a partially dug connection ahead of us.

The connection was tight and thrutchy, but nothing we hadn’t seen before. The directions were simplified not only by the guide ahead of us, but also by a cable running though the cave.  This was apparently put in to power the cameras for the documentary filmed in the 90s, and had never been removed. It ran from the entrance all the way into the decorated far reaches, and so was a useful tool to avoid disorientation for most of the trip.

Leading past the off-route (but apparently very pretty) Crystal Ball Passage, the cave quickly opened up to large stomping passage, although we didn’t feel the benefit for the most part because of the miles of conservation tape running alongside us. This tape was protecting some of the most beautiful and pristine decoration I’ve ever seen. Immersed by the appearance of dense straw forests, hanging in great white thickets, I hardly noticed the ever increasing larger stalagmites crowding in until we reached the Hall of the Thirty, where they gathered in force.

Despite its name, there are probably quite a few more than 30 mites and tites making that chamber their abode, but the classic cavers’ innumeracy does nothing to detract from the incredible effect of those many man-size (and larger!) speleothems of various hues. Adrian informed us that someone had recently been filming using a zipwire across the centre of the chamber. To my disappointment, this was only for a camera, and (to my knowledge) no adventurous spirit had flown among those gentle giants.

Moving on, we came to the area where the cave passes under the road. This is obvious without any survey needed, as a diesel spill from a now lost garage has leached into the cave and discoloured some decoration. As interesting as these pitch black stals appear, the strong diesel smell is quite off-putting, so we made haste through that area, making use of the handline to avoid touching those polluted pillars.

Passing by an area where drips were collected in a large tarp to provide water for conservation cleaning, we continued past vast tracts of eye-catching cave. Curtains, gower pools, thems of red, green, yellow, and blue. False floors of calcite above deep azure pools and drifting dunes of once waterswept sand. This cave really had everything. It almost became too much. Formation fatigue set in, and soon the awed gasps of the group faded, and were replaced with the usual chatting. Blood red stalactites that would have earned a pause in any other cave were afforded merely a cursory glance from the overstimulated visitors.

At length we came to the end of the cave. The final chamber ends in a choke, which is likely a good digging prospect, but being at the end of a long cave beyond a tidal sump I can’t fault anyone not wanting to dig though large boulders. Here we stopped for ‘lunch’ (though it was not yet midday), which consisted of a golden syrup or Jamaica ginger cake each. Hungers sated and thirsts slaked, we had a look at a sump below the chamber. This was an interesting whirlpool disappearing down a small gap, though Adrian informed us that it likely had little to do with the stream that once formed the mighty passage around us.

As we began our journey back the way we came, it became clear that we were a bit ahead of schedule for the tidal sump. We decided to clean up some of the formations in the name of conservation. Finding some spray pumps and brushes helpfully placed near the water collecting tarp, we discovered these were quite unhelpfully mostly broken. After a couple of false starts, I found a small spray bottle that worked, but was missing a nozzle, usefully spraying the water in two directions perpendicular to the intended target. This turned out to be a major innovation, as it allowed us to wash two stals at once. We stayed in the Hall of the Thirty until we ran out of water.

We were still a bit early, so we took a more gentle pace out of the cave. We had talked about checking out Crystal Ball Passage to ‘complete the cave’, but I walked past the turn off, and the others apparently silently agreed to not correct my mistake. The connection was slightly easier on the way back with the added benefit of gravity, and I lead the way, mostly using the electric cable as a reference. We all appreciated the return of water when we reached the streamway, and most of us stopped to ‘inspect the streamway’ before going any further.

We reached the tidal sump just before it was passable, so stopped to watch the water recede for a time. This was very impressive, as the level dropped noticeable before our eyes. The eyehole was soon above the water, and Adrian demonstrated this tightrope technique he had mentioned earlier. The rift was close on both sides, so the balancing wasn’t as hard as you’d think, and the eyehole squeeze looked quite forgiving. Jack and Helen both made balancing on the rope look rather easy, which was quite the trick because I almost fell in the water a few times, and took much longer than them. I was last through, so the lower water level leaving more of my body out of the water likely contributed to the increased difficulty, but I was glad to be through the squeeze and out the other side.

We were soon out the door, and the warm afternoon sun was a welcome sight. The walk back was even sweatier than the way there by virtue of it being uphill, but the hose left for kit cleaning at the top of the hill went some way to ameliorating this. We slowly changed in the car park, to the amusement of some climbers, and bid farewell to our guide. The early start meant that it wasn’t very late in the day, so we were back in Sheffield before sundown, although this didn’t stop Louise trying to fall asleep at the wheel.

All in all, a very pleasant trip. I didn’t check my watch very much but it took around 9 hours. The formations are definitely worth seeing, and it is a varied and sustained trip, making it a good day out. Our thanks must go to the Royal Forest of Dean Caving Club, who organise access, and our guide Adrian for an interesting and fun tour.