Sistema del Trave, Pit cave system in Picos de Europa, Spain.

Sistema del Trave is a karst system of three interconnected vertical shafts in the central massif of Picos de Europa, Cabrales, Asturias. Its entrances are the Torca de la Laureola at 2,042 m, the Torca del Alba at 1,975 m and the Torca del Trabe at 1,917 m. The system reaches a depth of 1,441 m and had 9,167 m of surveyed passages by August 1989. Underground streams join to form a river, and many conduits follow north-dipping thrust planes inclined at about 51°.

The cave entrance was discovered in 1982 near Bulnes village, marking the start of intensive geological research. This exploration led to complete mapping of the complex network and established the site as a major research area.

The system's name comes from the torca del Trave, its lowest entrance at 1,917 m, one of three separate openings along with the torca de la Laureola (2,042 m) and the torca del Alba (1,975 m). Cavers link the entrances through the network, and the underground river's final stretch can be followed for a short distance.

The three entrances sit at different altitudes: Torca de la Laureola at 2042 m, Torca del Alba at 1975 m and Torca del Trave at 1917 m, near Bulnes and the Jou de los Cabrones refuge. The system is a protected natural monument, so entry is for equipped cavers with authorisation; the underground river can only be followed for a short stretch.

Scientists identified a new genus of springtails called Ongulonychiurus living within the cave network, found nowhere else. This discovery revealed that the system provides habitat for specialized species that do not exist in the surface world.