Entrance 113 had been extensively explored by previous expeditions to a depth of about 450m. The surveyed route led across the head of a steep descent to "Ibbeth Perilous" pitch. This had not been descended since 1980 when a caver (see elsewhere in this journal) lost his helmet and light down it. In 1987, in the course of looking for extensions across the tops of a number of ramps near the entrance, a descent was made to the head of this pitch (although at the time it was not certain that this was Ibbeth Perilous).

A little way into the passage at the bottom of the entrance shaft, two parallel steep ramps descend for about 15m. The ramps have been free-climbed, however, an uncontrolled descent by Andy Farrow indicates that a rope is very desirable. The second ramp is blocked at the bottom, but a small hole gives access back to the bottom of the first. From here a short climb leads to a jammed boulder above the first proper pitch.

The shaft descends in a series of steps for a further 20m. These are free-climbable with difficulty. A 13m drop then lands on an ice-rock blockage, which previously contained the helmet and light, now recovered and pesented to their owner. This point has been named "Marathon Ledge" after Becka regurgitated a partially digested Marathon Bar over CHris from halfway up the pitch above.

The blockage was hammered out by a caver attached to a rope, after which two short drops led to a 6m pitch to a large chamber. This proved to be in the "Opera House" are of the original route.

The earlier survey suffered from a compass of questionable calibration, due to an encounter with a fridge (see Cambridge Underground 1984). The survey of the new extension has now allowed the orientation of the cave to be determined with greater accuracy. This is important, since entrance 152 enters the cave lower down (below the "Purple Pit"), and the entrance is only some 50m from an entrance into the Larchenhöhle system discovered by German and French cavers in 1987. A connection between 113-153 and the German-French entrance would add a significant amount of length to the combined system.