Tresviso Caves Project

Tresviso Caves Project Gazetter

T11: Cueva del Rio Chico

(Little River Cave, S2)

East, North:364443, 4789193 (nearby)
Coordinate Quality:GPS
Long, Lat:-4.6696946407055, 43.243328247029 (map)
Elevation (m):472
Length (m):1167
Depth (m):-108
Active Lead:
Survey Available:


Follow the track from Tresviso down to Cueva del Nacimiento (Cueva del Agua). Rather than cross the bridge to Cueva del Nacimiento, continue down the track on the north side of the gorge for approx. 200m to another bridge crossing the river. Follow the track on the south side of the gorge now, which trends up and meets the canal. If the canal is full of water… consider your options…

Walk along the outside of the canal for approx. 400m to an obvious ‘platform’ over the canal. If the water is low enough drop down into the canal and wade for another 400m, through tunnels, to another obvious platform. This is the Cueva del Rio Chico entrance with a sluice gate and the cave entrance.


The entrance has been modified by blasting and lies on the fault. A stream issues from the cave and joins the canal. Chico Entrance


The main passage has been enlarged by blasting and the stream is carried by a man-made canal for the first 200m. 50m in on the left hand side is an obvious pitch behind a low wall. This P6 leads to the Chico Nino series (2022).

Past the P6 the canal continues for another 50m to another low wall on the left and a small mined series of passages.

Slightly further on, in the main passage, is a climb in the roof, with obvious stemples in place. This has not been explored. Just round the corner is the first cascade, this is a c15, following a line of stemples on the right hand side. The climb continues for another 20m upwards to connect to a higher level, but the way on is to the left, following the water.

20m further on a large chamber is reached with an obvious man made concrete overflow channel. A climb to the left closes down quickly. An obvious ramp behind and to the right, as you enter the chamber, leads to 50m of large, inclined passage, with an undescended pitch at the end (possibly back to the main stream below, but unconfirmed).

A hole on the right connects back to the top of the p15 cascade and immediately opposite this is a small ramp up, that leads to an awkward c6 into small chamber. Heading down, the passage gets bigger and there are holes on the left, down to the stream and 2 obvious ramp climbs in the roof.

Following the passage down eventually leads back to the stream, left connects, after 30m to the ‘overflow’ chamber but the main way on is to the right. The main stream can be followed, via increasingly deeper sections or a number of obvious short bypasses can be taken (follow the iron stemples) to re-join up at a shallow cascade and either a final wet section of another bypass to reconvene at the main sump pool.

There is a draughting but impassably tight hole above Sump 1 and a possible climb on the left hand side as you enter the sump chamber.

Sump 1 is 30m long, reaching -10m depth, before reaching a small airbell and a little cascade. Sump 2 is over 200m long, reaching a depth of -80m. It continues in a similar fashion but at depth (2022).

Chico - Nino Series
Descending the pitch behind the first wall, approx 6m to rebelay on miners' stake and deviation approx 8m. The route below, about 3m, is blocked with rubble, a square cut adit with concrete floor leads off, water is met, this sinks on the left hand side into more mining debris and possibly a buried metal doorway/ sluice, continuing the water enters from a choke at the top of a slope, probably from the main Chico cave above.

Engineers had worked extensively in the cave, penetrating as far as the sump, presumably when the canal and hydro were built.


L.U.S.S. (1974-1977)
Caves & Caving No 28.
Caves and Caving No. 36
SWCC 1986 T.C.P. (2022)


Chico Entrance