Tresviso Caves Project

Tresviso Caves Project Gazetter

T145E: Pozo Natacha

Area:Mazarrasa Mines
East, North:0, 0
Coordinate Quality:No location
Long, Lat:-7.4887438971664, 0
Elevation (m):0
Length (m):0
Depth (m):-279
Active Lead:
Survey Available:


There is no natural entrance to Pozo Natacha , it can be entered via Pozo del Castillo or Castillo IV (Segura 2) with the latter being the easiest and quickest entry point. The following description assumes entry via this route.

This is contrary to parts of the 1981 Les Speleois Dromois report, which suggested Pozo Natacha begins with two pitches from the surface. However, on investigation this is due to confusion at original exploration, and subsequent inaccuracies on surveys. The entrance and two pitches shown on some surveys and described in the 1981 report are actually the first pitches in Pozo del Castillo, but incorrectly assumed to be a new cave. This mistake has been rectified in some literature, but not all.

For the purposes of this description the overall system and main entrance is referred to as Pozo del Castillo, Pozo Natacha is a sub-series of pitches within the main complex.


Left hand passage at the main Pozo del Castillo junction, when entering from the Castillo IV (Segura 2) entrance.


The Castillo IV (Segura 2) entrance is a driven mine adit 2m x 2m. The first 30m is in knee deep water before becoming dry and continues for another 70m to the main Pozo del Castillo junction.

Natacha Upper Series
At the main Pozo del Castillo junction, if entering from Segura 2, taking the left hand junction leads immediately to a wooden ladder on the right. At the top of the ladder a route to the right leads up into a window over a short climb down. A further climb up on the left leads to a short section of passage than connects with the route left from the top of the ladder.

A large passage continues upwards, with a short section down on the left leading to a dangerous collapsed winch platform above the first Pozo Natacha pitch. The pitch head is unstable and it is not recommended to descend the pitch from this point. The passage can be followed upwards once more but passes a number of false floors over the pitch head and following this route is not recommended. Instead following the parallel large passage continues upwards across numerous cross passages that all end in dangerous collapses and have not been fully explored. A small pool is passed on the right before a final steep ascent to a further (more natural looking) area of collapse. The passage continues upwards through more collapse but has not been pushed to a conclusion.

Taking the left-hand junction leads immediately to a wooden ladder on the right. This leads up a number of difficult climbs to further mine workings and a dangerous collapsed winch platform above the first Pozo Natacha pitch. The pitch head is unstable and it is not recommended to descend the pitch from this point. There are a number of passages in this area that have not been surveyed and the completeness of exploration is unknown.

Pozo Natacha 1983 series
Back at the junction, straight on leads, via further mined passage for 20m, to a 4m long ledge approximately half way down the main pitch with the winch platform high above. The pitch is a large and impressive shaft of 30m, from this point, with dimensions of 7m x 15m and is best rigged from the left hand wall in two sections, down to a ledge 8m below and re-belay over the lip to get a clean hang to the bottom. A 35m rope is sufficient.

From the bottom, a loose scree slope is carefully descended to a short meandering rift which turns to the right. The rift opens up after a few meters and a 4m drop lands on a ledge in the rift. The rift is followed in the same direction by climbing 2-3m onto a wedged boulder. Care should be taken as the floor is not solid

From the top of the boulder the meandering rift is followed at approximately the same height for around 6-7 meters until it opens up and an obvious stance which allows a clean hang to the sloping debris covered floor approximately 5-6m below. A 10m rope is sufficient.

From the bottom of the slope the rift can be seen to continue ahead at the same level but the way on is to descend through the narrow slot at floor level. A hang of approximately 3-4m allows a tight descent onto a wedged rock where a re-belay can be set. A clean hang can be achieved for the remaining 10m but care must be taken on the return as hauled bags can dislodge loose debris on the walls. A 15-20m rope is preferable to allow the loose slope at the bottom of the pitch to be descended or ascended more easily on the return.

From the bottom of the slope a small step up gains entry to a chamber opposite which affords some protection from falling debris above and at this point it is safe for the next caver to descend the scree slope at the pitch head and the full pitch.

Another meander, approximately 1m high, is followed for 50m initially at floor level, to a tight squeeze at the top of a 17m pitch (20m rope). At the bottom of this circular shaft a small hole in the floor can be seen in opposite. Care should be taken descending as it's not entirely obvious what is supporting the wedged blocks. A clean hang is not possible and it is mostly an assisted climb / squeeze. The descent can be taken in 2 parts, the first 2-3m drops into a small chamber which allows bags to be passed down and a second 'Y' hang drops a further 2-3m through a slot into a descending rift.

The rift is followed for 20-30m to the head of an 8m pitch which lands in 4m wide aven. The cave at this point is -133m deep. Above the last pitch is a small aven with water entering, this is the final pitch of Torca del Reloj (T304 - Clockwork Pot).

A small active stream way is encountered at this point and leads after 10m to the edge of a spray lashed 20m pitch (6m in diameter), best rigged on the right. At the bottom quickly leads to a 50m pitch.

At the bottom of the pitch a short rift leads to a 25m pitch that is split into two sections and then another 15m pitch (both can be rigged with a 65m rope). The stream disappears down an impenetrable rift at the base of the pitch.

A small ledge on the right gives access to a crumbling fossil rift for 30m, then a descent of meandering ledges of 12m and 7m (rig with a 45m rope from top), leading to a pitch of 25m in a smooth sided shaft, with water entering at one side. At the bottom is small rift ending in a very tight squeeze above an 8m pitch.

At the 1987 limit of exploration there is a small rift ending in a very tight squeeze above an 8m pitch. At the bottom, the rift continues and has been enlarged to create a 6m drop to another tight meandering rift above an undescended 20m pitch. (-309) The possibility of entering the pitch is extremely remote as the rift would need to be enlarged down for approximately 2m.

There is a strong draught in evidence throughout the cave and the end is only 90m south and, including the undescended 20m pitch, level with the end of Pozo del Castillo.


L.S.D. (1981)
T.C.P. (2017-2018)


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