Overview: initial sub-horizontal passage zigzags southeast above various rifts in the floor. These seem to be formed on a series of hading joints, giving various vertical routes downward. Two principal routes appear to be formed on the same major joint, and both drop some 150m to reunite in a section of big phreatic level trending NE-SW, but blocked in both directions. The original way is still called the Left Hand Route, whilst the later, and perhaps easier and drier route is known as Garden Party.
This is now normally entered at the Dewdrop junction, but was named from a point of entry below Becka Falls. Right (east) from Dewdrop Junction is zig-zag and is punctuated by several undescended holes in the floor [C1988-161-08] before changing back to a hading rift at a sharp right corner. The rift soon leads south to Arrow Chamber with several possible ways on.
The main way on is Butcher, found by climbing down under some boulders by the left hand (NE) end of the far wall of Arrow chamber (the eponymous arrow points to the relevant boulder). The 45m pitch lands on a choked shaft floor where a further parallel shaft can be seen on each side through slots in the walls. To the left has been known, apparently erroneously, as Candlestick Maker, to the right, also apparently incorrectly, as Baker. The latter has an aven above which was thought quite probably to be one of the shafts from Arrow Chamber. Subsequent exploration of Pointless pitch suggests that this is probably not the case. A large eyehole into the shaft on the right shows the way on, being a traverse followed by a 10m pitch: the Oubliette.
Walking across below a huge aven and sliding left behind a rock into a tight rift, leads into a series of shafts which continue down with ledges hindering the descent, until a large, wet, black hole is found. This is Niflheim, 'A realm of freezing mist and darkness under one root of Yggdrasall (the world tree) which hell lies within'.
Niflheim is a 51m very wet pitch which lands on a rock bridge, Bird's Eye, about 45m down and the limit of exploration in 1988 [C1988-161-02]. Here the shaft splits - most of the water goes down the southwest (French Connection) side and the rope goes down the other side to land on a ledge about 7m above the floor. The way on is down a pitch/climb to Ragnarök. To the left is where Garden Party lands. Traversing round to the right leads into a 5m canyon passage which emerges in the wetter part of the shaft at the head of French Connection Pitch (1989). The 9m drop leads to French Connection Chamber, which is where Drunk & Stupid debouches.
At the start of the Left Hand Route, as entered from Becka Falls, is a short length of passage with a 100° right turn, leading very quickly to the normal entry point at Dewdrop Junction. The false boulder floor of this passage was excavated just at the bend in 1992 (hence the subsequent need for a traverse line when going from Dewdrop Junction towards the Right Hand Route).
Down the hole, Garden Party starts as a 6m pitch into a steeply hading rift. The area, Lazy Labyrinth, is labyrinthine with numerous pillars and bridges. The pitch and continuing rift can be descended with a handline (originally rigged in sections of 4, 7, 6 and 2m) until a final 8m angled pitch leads into larger passage (35m rope). To the right is a boulder choked passage, to the left is a chamber with two ways off on the right. The upper (more obvious) of these leads to complex three dimensional phreatic maze situated above an undescended pitch with a long drop [C1992-161-06].
The lower and less obvious leads to SHAT Pitch (Should Have A Traverse bolt) with a short traverse line rigged from a natural. SHAT is a 10m pitch from a bolted Y-hang into large hading rift. There is a sharp right turn after 15m and a couple of climbs. At this corner is an undescended pitch which connects (visually) with Hare Rift about 15m down. Stooping right leads to the head of the very large Tortoise Pitch.
A 7m ramp drops to a rebelay round a corner on the left in a place where you would definitely not rig behind a flake. From here, access can be gained to the parallel rift, Hare, which can be freeclimbed instead of the pitch (except the first and last 5m). Tortoise and Hare have access points at numerous places, and much fun can be had as one prussiks and the other sticks their head out all over the place.
Tortoise drops in 6m, 10m and 8m sections (bolt rebelays) to a ledge which is the bottom access to Hare, and thence to the rocky bottom. Climbing into Hare at the first rebelay and turning right, back under the ramp at the head of Tortoise, leads to views onto at least one big pitch [C1992-161-07], and the climb down.
The bottom of Tortoise is drippy and choked. The way on is a 2m climb on the opposite side to the pitch, into a narrow passage. About 5m along this, a 2m climb up to the left leads back to Tortoise, and then, via a traverse, to a view onto a big pitch [C1992-161-08], presumably the same as can be seen from part way up Hare (although it has been given a different QM number), and from part way down Parallel Processing.
Continuing along the narrow passage, a small hole in the floor is passed. This gives a very tight bypass to a nasty climb, Hangover Hang, about 10m further on (needs a 9m handline). The floor here is very unstable, and fell down on the derigging 1992. It needs a traverse line.
Parallel Processing is a fine pitch, approached by a short traverse line (one natural, one bolt) and rigged from a Y-hang on a 25m drop to a rebelay, then 15m to another bolt at a ledge on the left. At this point is a large window which intersects a parallel (unexplored) shaft thought to be the same as seen at C1992-161-08. The final section is an 11m hang.
Continuing down gives climbs and a pitch, Windowed, in two sections, with a massive boulder across the passage at the top. This is rigged as 8m from a Y-hang (one bolt at near side, natural at far side), to a short (1m) climb down and back up again to reach the single bolt rebelay of an 8m hang in the bottom of a much deeper pitch, finally debouching into Ragnarök at the same point as Niflheim on the original Left Hand Route.
Directly down from the ledge at the bottom of Niflheim, is a 6m pitch to the floor (climbable with care, but perhaps best laddered). From here there is a 1m diameter wet hole which goes 10m to an extremely tight and scrotty 6m pitch C1989-161-14]. This hole takes the rest of the Niflheim water, and so is very small and wet - checked out in 1991, but appears to continue.
From the foot of the ladder a walk of 5m southeast through gaps between some large fallen blocks gains the bottom canyon of a large fossilised phreas, Ragnarök, at a T-junction. Climbing 5m up the boulders leads to the phreas at a higher level, separate from the lower canyon for about 20m. Turning right in Ragnarök (SW) leads to a large sand ramp which reaches the roof after 10m. Turning left, the canyon narrows over the next 20m to where it is choked with boulders at ground level, but an easy climb up 2m at the start of the boulders reaches the passage proper. It is about 8m wide with sides sloping down towards a central 0.5m wide canyon in the floor which can only be seen occasionally as it has largely been covered with rock fall and sand.
After 25m and 40m, ways on the left (NW) lead into Ambidextrous, a somewhat involved route through to the Right Hand Route.
By the Ambidextrous turnoffs, a number of routes down into the boulders lead to a p17 followed immediately by a p20 into a short passage, too tight at both ends. The Ragnarök phreatic route continues for another 30m of passage (with a choice of either a 2m climb or a squeeze through large blocks to get past one particularly large boulder) leading to the Black Lagoon, a perfectly flat area of cracked mud at the end of the passage, presumably a silted-up sump. Hellgrind and Trehala go off from here.