The consequence of this success was that a number of people wanted to spend more time in Matienzo the following year. For various reasons they decided to give up their jobs and stay in Spain for upto six months. The first to arrive were Lank and Buddha, in March. Unfortunately they were to experience an extremely cold and wet Spring, and in fact 1975 was the wettest year for more than half a century.
Thanks to the longer time available, they were able to programme a complete re-survey of all the caves in the valley, and the caves of Hozana and Cueva del Risco were the first to receive their attention. Each cave was to be situated correctly and, as only large-scale 1:50,000 maps existed at that time, this meant carrying out their own surface surveys. By the end of the expedition these had covered the entire area between Riba and Riaño. One of the first rewards was the discovery of Cueva de Anderal III - its entrance was easily visible through the leafless trees. Later, at the end of April, Anderal II would be extended through galleries running beneath Anderal III. In Risco several new side-passages to the Pintó Gallery were surveyed. The next area to be studied was El Naso. Few new finds could be claimed, but they produced the first surveys of caves like Patatal and Coburruyo, and positioned each cave on the area map. In this area they obtained the help of Antonio el del Pontón, who had once worked with SESS, and he showed them several new entrances, such as Sima de los Hoyos.
The first important finds came on 13th and 14th May, in Cueva Tiva, up the aven climbed by Geoff Yeadon the summer before. By digging through Sandstone Passage, they found the complicated series of passages which connected with Risco. Thus they established the third entrance to the system, which now reached 8km in length.
Reinforcements joined the expedition in the middle of April and early June. Throughout this time they continued revising all the known caves (such as Cuatribú, Subterranea and Concebo, Emboscados and Arenal). In Torcón de Cubija they were able to make a small extension by climbing a calcited aven at the end of the cave. Several shafts were descended for the first time, including Sima de la Chova, Cruz Llorada, Rocabado and Sima Jaime. In the next shakehole to the latter they found Cueva A.B.I., consisting in a large chamber.
About this time they also visited Cueva de Coverón and retraced the main passages described by SESS. In the left-hand series Buddha climbed into a passage and a pitch dropping into the Minimaze. This ended at a blowhole which was dug out, leading to the discovery of the long vadose stream-passage. A little later in the expedition a tree was cut down outside the entrance and used as a scaling pole to reach high-level passages at the end of the right-hand series. In all, over 2km of new passages were added to Coverón.
By early July the full summer expedition was underway. One of the first caves to be visited was Uzueka, and work was centered in the area of Pig's Trotters Chamber, just before the sump. Two series were explored, Sima Baz and Sima Dave. In the former Baz Davies and Wayne dug out a chain of sandy chokes which appeared to by-pass the sump, but which then ended in a solid boulder-choke. Nevertheless, Alan (Starkers) Martin was able to move one large boulder to open the way to the Gorilla Walk and all the important passages of Uzueka. These were explored and surveyed over a number of trips, each one making further progress into the system. The Near and Far Stomps ended at another sump, then Crossover Passage led to the 3rd River. Next the Astradome was found, and finally the boulder choke was passed to enter the chambers of Armageddon.
At the time the trip to the end was considered quite hard going, and six hours was quoted as "motoring to get to the end and back, let alone start exploring anything", so Armageddon was in fact only entered once. As it happened, on the day that it was discovered, 8th August, two people became lost in the system and decided to wait for help. They were eventually found early the next day, 17 hours later, at Obvious Junction.
But even without a dye-test, it seemed certain that the river in Uzueka must join the Matienzo water, and resurge at Secadura. Thus it was already clear that an extensive system had to exist linking those three valleys.
At Riaño other caves were discovered too; Chestnut Hole and the 92m deep Torcón.
But other major finds were being made in other parts of the area. Geoff Yeadon and Stuart Davey dived the final sump in Cubio de la Reñada. After 30m they surfaced at the start of Reñada II, about a kilometre of large active and fossil passages. The divers also examined the Nacimiento del Río Clarín in San Miguel de Aras, passing two short sumps to find several hundred metres of passages.
Other people, including cavers passing through Matienzo on their way to or from Picos de Europa, were involved in the descent of Torca de Llusa, which choked at a depth of about 150m. This was the first attempt at tackling the big shafts on Mullir using single rope techniques.
Many other caves had been looked at; Las Cosas, La Cuvía, Volvo and Seta in Matienzo, and Elegante in Secadura, while other draughting holes were examined at the head of the Llueva Valley.
One of the last caves to be surveyed was Cueva de la Espada in Riaño. With all this activity it isn't surprising that even untrained explorers should make a number of archaeological finds. Lank had found a palaeolithic bone point in Risco, and a Bronze Age skeleton in Rascavieja, and Cueva de la Espada got its name from the bronze sword found there by Dave Linton. This is now on display at Santander Museum of Prehistory.
The expedition concluded as another great success. The finds in Uzueka alone were probably the most dramatic and important ever made in the area. The warm welcome the cavers had received in the village in 1974 had solidified into real friendships. The contacts with Juan Carlos Fernández and Alfonso Pintó were maintained, while other members of SESS had spent a couple of days with the expedition at the start of July. Once again, the report was brought out within a month of returning to Britain, with a great improvement in quality over the 1974 edition.