The Aggy Grand Circle is a real sporting classic with a good mix of scenery and obstacles and very little repetition. This trip takes in two very different streamways, a selection of climbs, big sandy passages, water-worn rift passages and some very deep water. This certainly not a novice trip as both the length of the trip and the various obstacles along the way require some endurance, so allow plenty of time to complete the circuit. Time taken on this trip varies depending on group size and familiarity with the cave, but you should allow at least 7-8 hours. This route description here is in the clockwise direction, which is generally considered the most practical as you’re well over halfway before getting a full soaking in Deep Water.

Warning - This is not a trip to be done after heavy rain as sections of Deep Water and The Narrows can sump. If the Main Streamway is in full force and difficult to progress through then it’s wise to turn back and return through Southern Stream.


Cowstails are useful for High Traverse. There is a fixed line to clip into as a fall and rescue from here would be a serious matter.

Route Description

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.

Beyond the initial rifty sections, at a point when the passage takes on a larger scale (just after you emerge from a slot behind a boulder), look for a climb over the rocks on the left. This provides the easiest route of continuation. Missing this will mean an awkward climb up to a squeeze to gain the higher level further on. First Boulder Choke is reached where there is a red-and-white tape across the passage. On the right hand side of the passage, opposite a sign about roosting bats, a gap between boulders leads to a 2m climb down. After this go forwards a few metres and turn right into a small passage, then almost immediately head down and left again into a passage containing a small streamway (missing this will result in a fairly lengthy detour in the wrong direction ending at a dig). After this, the way through the choke is fairly straightforward, just follow the well-worn route. 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. Shortly after you are forced to climb down into the middle of the passage the junction with Main Stream Passage is met. Since you are doing Grand Circle in a clockwise direction, this will be your return route. The continuation of Main Passage and the route to Southern Stream is upslope on the left. This part of the cave is remarkably pleasant and the passage is undoubtedly one of the finest in Wales – make the most of this while you can as the following section is quite the opposite!

Aggy Entrance (key required)
Rift squeeze in the Entrance Series
Entering larger passage in the Entrance Series
The blue sign in Baron’s Chamber
Main Passage
Main Passage
An impressively large section of Main Passage

Southern Stream Passage

There are a few passages heading off in this section but the junction 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. Continue over boulders, pass through a constriction, then a short distance beyond a hole down between boulders leads into Southern Stream Passage. This is our route and the start of a section of caving of far less sizeable proportions. The continuing higher level route leads to Sandstone Passage and Upper Southern Stream.

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 250m further the smaller Second Inlet, equipped with a drinking cup, enters from the right. This is roughly the halfway point. 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 2m climb.

The going is comparatively easy and much more pleasant after the waterfall, with occasional climbs up and over boulder obstacles. Look out for the short rope climb and rope traverse in a section where the upper part of the passage is significantly wider. This leads into Gothic Passage, and is the usual route taken on the Grand Circle. This is not only shorter, but takes in more interesting passages and is also handy for anyone wishing to combine the Grand Circle with a trip to Maytime or Priory Road and Iles Inlet (though both of these would add a significant amount of time to your trip). However if you are enjoying Southern Stream so much that you want to skip this section and continue on to the bitter end then continue along the streamway. 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.

The drinking cup halfway along Southern Stream
The waterfall rope climb in Southern Stream
Rope Traverse from Southern Stream into Gothic Passage

Gothic Passage to High Traverse

To take the more normal route from Southern Stream climb the rope to the wedged boulder and use the fixed line to traverse across. Gothic Passage starts as an easy walking passage but quickly lowers to a crawl before arriving at a T-junction. Ignore the left-hand turning as this leads to Priory Road and Iles Inlet. Instead turn right along a sandy crawl which varies between hands-and-knees and flat out. This emerges into the side of a large sandy passage (Synchronicity) with three obvious taped routes heading in different directions. Our route is the right-hand one and is fairly well worn and obvious. In the other directions, left soon closes down, while straight ahead is Resurrection Passage, which is the route to Maytime.

After heading right at Sychronicity, a short crawl then emerges into a very impressive phreatic passage of mostly easy walking. Following the obvious taped route soon leads to the large sandy balcony of High Traverse with the remains of an old camp and an inflatable skeleton. This is high above Main Stream Passage with ropes in situ to aid the descent. If you’ve brought cowstails, you may want to use them here. Follow the fixed rope along the rock ledge on the right, then climb down a rope with knotted loops to reach the streamway below.

The remains of the old camp at High Traverse
The balcony at High Traverse
High Traverse rope climb down to Lower Main Stream Passage

Main Stream Passage

One thing you’ll soon notice about Main Stream Passage is that it’s really slippery, so progress with care. From here we head upstream (downstream leads to Sump 1 and the connection to Southern Stream Passage that you would have emerged from if continuing to its end). Upstream, the water is mostly quite shallow with lots of clambering over very slippery rocks. A small waterfall in a narrower and deeper 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 this 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, this has a reflective marker and is easy to spot. Though relatively short, this can be awkward; it’s possible to use the loops on the double rope as footholds if needed. Above this, a further easier rope climb leads to Biza Passage. This is completely different to everything else so far, an ascending rift passage with a series of phreatic switchbacks. This is a good chance to get warm again before the next section of cold water!

Biza Passage is roughly the halfway point of the Grand Circle and is also the area that many people find confusing – having to backtrack due to not finding the way on is not uncommon. However, this can easily be avoided with the knowledge that whenever there is a choice of route, heading up or left will take you in the correct direction. Be sure to avoid the two passages heading off on the right (Bat Passage and Sump Passage) as these continue for quite a distance before ending very close to becoming a loop.

Generally the route through Biza is relatively well-worn so you know you’re going the right way. However when approaching the end of the passage everything starts to feel more like a dig than a trade route and the floor becomes quite stony – don’t lose heart, stick with it! When you spot the yellow wire on the floor you’re definitely on track and approaching 4th Boulder Choke. This starts with a short crawl through a constriction, followed by a corkscrew descent through the choke. This has some loose rocks so is best done one at a time. Below this another short descent through boulders regains the streamway.

Continue upstream and very soon you’ll reach a boulder slope.  Go up and over this.  Not far beyond a large boulder blockage is met, this is 3rd Boulder Choke. Climb up through the boulders and follow the obvious worn route to emerge from the top. 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.

Lower Main Streamway
The climb up to Biza Passage
Towards the end of Biza Passage
The first part of the climb down from Biza
Awkward boulders before Deep Water

Northwest Junction to Main Passage

Northwest Junction is a confluence where Turkey Streamway meets Main Stream Passage. Here we turn right to follow Main Stream, while left is Turkey Streamway – the route to the Inner/Outer Circles and Sand Caverns. The water soon becomes shallow, and the floor is again slippery. Further along, Ochre Inlet has 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: the route recommended here is to climb up and over this to reach a fixed rope climb. Use the ropes to climb to a chockstone, then another short climb up to Keyhole Chamber. Here there’s a canyon in floor and a fixed line on the left – be careful not to slide into the canyon at the slackest point. If you prefer, you can avoid this problem by jumping across the canyon at the narrowest sections instead.

If you wish to avoid the rope climb altogether and don’t mind a soaking, then continue following the streamway and after a low and wet crawl, look for a polished climb corkscrewing upwards through boulders. This leads to a small boulder chamber and another short climb. The easiest way to do this is to climb up next to the boulder at the leftmost end of the higher-level ledge, then and go behind it and cross the narrow ledge to reach Keyhole Chamber where you’ll see the other route joining on the left.

Whichever route you chose, continue along 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 on a climb is met, but instead of climbing directly follow the stream leftwards 5m to a boulder choke, then climb to a high level tube heading back. A fixed rope at the end of this assists on the exposed corner, and a short rope climb soon follows.

Ignoring the higher level passage on the right, continue 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! Simply take the route of least resistance until you reach a low stream passage joining from the left. Leave the stream here, the route on is straight ahead over the boulders where you’ll find the crawl connecting back to Main Passage. Your circle is now complete, so now it’s just a case of heading out the same way as you came in – making sure that you don’t miss the climb down to the Entrance Series and remember to turn right at every junction.

Climbing the rope up to Keyhole Chamber
Crossing the canyon in Keyhole Chamber
The climb near 2nd Boulder Choke

Written by Adrian Fawcett and Mandy Voysey. Photos by Matt Voysey.

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