At the 1992 exploration limit of the inlet heading towards Rio Lastras is a 2.4m high waterfall emerging from a narrow canyon in friable, black rock. This can be scaled to a squeeze and then climb out of the streamway up into a large breakdown chamber. This chamber can be followed South over big blocks until it reaches a window down back into the passage below the waterfall, and a traverse over a large hole above this passage which seems to head into a large continuation heading back towards the central portion of the cave. A steep climb on the left just back from the traverse gains a narrow passage in the roof ending at a bold step over a deep hole onto a balcony that is beyond the traverse. A short pitch down will enter the continuation. This was partially bolted as a down pitch before the drill failed, so this needs to be completed. The bolt here SHOULD NOT BE USED.

Back at the climb up into the breakdown chamber, the main upstream canyon has not been pushed, but is presumed to connect up to the passage about to be described. This section needs checking for side-passages. Halfway up the climb, an apparently blind passage continues by squeezing round the side of a large block. This continues easily for 20m or so until the passage dimensions reduce to a low, tight crawl. The crawl can be followed through a squeeze, and the passage beyond was dug past another large block. After this point, the passage emerges back in the roof above a stream trench, presumed to be the upstream continuation of the waterfall stream. Continuing upstream here, the trench becomes shallower until the stream is flowing in the floor of the passage itself. A crawl in the stream can be avoided via a pair of squeezes through calcite. There may be higher level passages at this point needing investigation. The main stream passage continues until the water emerges out of boulders and the about 30m further on a large aven draughty aven is met. This is 11m high with a large passage in the roof, possibly running North-South. 4m up from the base of this aven is another waterfall trench, again in the same black, flaky rock. Progress here will either require bolting the aven or maypoling up the waterfall and hoping the trench is wide enough to pursue. The rock in the aven is somewhat flaky and may require long thru-bolts to scale. The passage at the top is large and of a different character in nice limestone. It looks like some sort of main trunk passage.