© Chelsea Spelaeological Society - Updated June 2022
CHELSEA SPELÆOLOGICAL SOCIETY Caving in Wales, the South of England, and beyond


Written by Adrian Fawcett

Entrance Series to Main Passage

The rule to remember in the entrance series is always turn left on the way in. There are a number of junctions where the passage on the right should be ignored – some of these go a considerable distance! On the way out, always turn right. First Boulder Choke is reached where there is a red-and-white tape across the passage. On the right hand side of the passage a gap between boulders leads to a 2 metre climb down. Then go forwards a few metres and turn right into a small passage. Almost immediately go left again into a passage containing a small stream. After this, the way through the choke is fairly straightforward. After about 50m climb up steeply, and you will emerge into Main Passage. Note carefully the position of the hole down into the boulder choke as it is easy to miss it on the way back! The rock with the blue sign on it is a useful landmark. The easiest way along the first part of Main Passage is to keep to the left hand wall. Just after you are forced to climb down into the middle of the passage you meet the junction with Main Stream Passage, the connection involving a few metres of hands-and-knees crawling. Since you are doing Grand Circle in a clockwise direction, this will be your return route.

Southern Stream Passage

The junction of Main Passage with Southern Stream Passage is easy to spot – the floor drops away on the right hand side of the passage, and a clamber down a boulder slope leads into a dry passage. Pass a constriction, then a short distance beyond a hole down between boulders leads into Southern Stream Passage. The continuing higher level route is Sandstone Passage. The first section of Southern Stream is mostly stooping passage and relatively free of obstacles and there is normally very little water. First Inlet enters from the left, and after another 250 metres further the smaller Second Inlet, equipped with a drinking cup, enters from the right. From here onwards there are more obstacles to impede progress. Often there is a dry alternative to crawling in water, although in a couple of places this is unavoidable. At one of these the roof lowers until it is impassable, but on the left side a narrow ascending slot provides a bypass. Soon after this the going starts to get easier with some open walking passage, which suddenly arrives at the top of a small waterfall. A handline has been provided for the 2-metre climb. The going is comparatively easy after the waterfall, with occasional climbs up and over boulder obstacles. Look out for the rope traverse in a section where the upper part of passage is significantly wider. This leads into Gothic Passage (see next paragraph). Continuing down Southern Stream, the passage becomes narrower and taller and there is evidence of periodic flooding. There is one place where there is no way on at stream level, and an awkward climb up and back down again must be negotiated. Shortly afterwards, a junction with the large gloomy Main Stream Passage is reached.

Gothic Passage to High Traverse

This route cuts off the corner compared with going to the bottom of Southern Stream, so some would argue that it’s not then a proper Grand Circle! It is often used when Grand Circle is combined with a trip to Maytime and Sump 4. Beyond the rope traverse in Southern Stream Passage, Gothic Passage starts as an easy walking passage but quickly lowers to a crawl before arriving at a T-junction. Left leads to Priory Road. Turn right along a sandy crawl which varies between hands-and-knees and flat out. This emerges into a large cross passage – Synchronicity. Left closes down, while straight ahead is Resurrection Passage. Turn right, and after a short distance bear left into a crawl as the big passage swings around to the right. The crawl soon enlarges into a pleasant mud-floored phreatic passage which contains remnants of High Traverse camp. This passage meets Main Stream Passage at high level, and a rope handline is provided for a short traverse and subsequent climb down to the stream.

Main Stream Passage

It is a short wade downstream from the Southern Stream junction to Sump 1. Non-divers can reach the other side of sumps 1, 2 and 3 via Resurrection Passage (reached from Gothic Passage or High Traverse). Going upstream the water becomes shallower until you are clambering over very slippery rocks which are a feature of this section of streamway. A small waterfall in a narrower section is best climbed from the ledge on the left. The next landmark is Quarry Corner – a big boulder-filled chamber on the right. Soon after a pool is reached with a small waterfall at the far end. There is little to choose between going around the left or right side of the pool: both involve deep water. Immediately beyond the pool against the right hand wall is the Biza Passage rope climb. These lead up about 25 metres to Biza Passage, with its series of phreatic switchbacks – a chance to get warm again before the next section of cold water! In the few places where there is a choice of route, up or left will take you in the right direction. Eventually the passage becomes a low crawl over cobbles, and this leads into 4th Boulder Choke. The choke is quite constricted and a bit loose, so take care here. With a tackle sack, you may find it easiest to keep the bag above you. A chamber is reached, and from the bottom corner the route continues between boulders to rejoin the streamway. Continue upstream, and very soon you reach a boulder slope. Go up and over this. Not far beyond this is 3rd Boulder Choke. Start in the stream at the right hand side, and after about 10 metres, look for a way up to the left. After a bit of route-finding you will emerge from the top of the choke alongside the left wall. Next comes Deep Water – a chest-deep section of streamway. Actually there are a series of short deep-ish sections. The only out-of-depth section is The Narrows, and with a bit of care it is possible to traverse along this rift until it eventually becomes shallow enough to stand on the stream bed. After this comes more big stream passage with yet more slippery rock. Eventually you will arrive at a pool where Cascade Inlet enters from the left, and just beyond this is Northwest Junction.

Northwest Junction to Main Passage

Turning right at Northwest Junction the water soon becomes shallow, and the floor is slippery until Ochre Inlet, where there is another drinking cup. Continuing upstream there are a series of boulder obstacles but no route description for this section is necessary. At a well-polished vertical rock there are two options – one option is to continue at stream level and climb up 50 metres further on. The other option, described here, is to clamber on top of this rock then climb up just beyond where there is a handline hanging down. It is easiest to get onto the chockstone from the other side, then make use of the rope for the top section. At the top is Keyhole Chamber. Cross the trench and follow the left hand side. At one point it is necessary to cross and re-cross the trench – best done quickly! Carry on to the far end of Keyhole Chamber, and climb down the boulders to the stream. This leads to the first part of 2nd Boulder Choke where a grovel in the stream is unavoidable. Climb up through a hole into a small chamber, go left through a tube and back down into the stream. A little further is a climb up on the right, but the easiest route involves going 5 metres further, climbing up and coming back on yourself in a high level tube, then turning left at an exposed corner. A further short climb follows. Ignore the passage off to the right and go forwards into an easy-going passage, which leads into the second part of 2nd Boulder Choke. A gap between boulders is followed soon after by a squeeze, and a boulder slope back down to the stream. The next section of passage is not really worth the effort to describe! Suffice to say, the landmark to look out for is a fairly obvious stream junction. In between the two branches of the stream is the connecting crawl to Main Passage, where you re-join your outward route.