which has been partly buried by the grassy slope (normally covered by rocks spelling out the names of visitors to the cave). The sea rarely enters the sea cave nowadays (only during spring tides) as the area has undergone isostatic uplift. The present-day cave is long up to the terminal sump at the rear of the third chamber/passage. The cave travels further, however, as an active stream of notable size resurges here at all times. Previous dye-testing has linked an underwater passage to an initial sink point in the Allt Smoo stream about upstream from the main waterfall, implying that the cave system is at least twice as long as once thought. Cave divers from the Grampian Speleological Group have dived this sump for a distance of about , although large volumes of silt and peat in the water have prevented further exploration. It is worth noting that the main waterfall is often dry and will only become active once this upstream sink overflows. Archaeology Archaeological investigations in 1995 turned up Neolithic, Norse and Iron Age artifacts but the majority of the artifacts from the cave were related to Viking/Norse or medieval activity. Fish bones, marine shells, plant remains and mammal and bird bones indicated the processing and consumption of marine and terrestrial foods. Iron slag and boat nails led the archaeologists to surmise that boats were repaired in the sheltered inlet. Four radiocarbon dates from Smoo Cave and Glassknapper's Cave provide evidence for use of these sites between the eighth and 11th centuries AD. The cave complex is protected as a scheduled monument. Tourism The cave is located east of the village of Durness and is presently served by a car park, toilets, stairs and walkways. Plans are being considered for access improvements for the estimated 40,000 visitors it receives annually. Tours of the cave also operate during the summer, taking visitors to the inner chamber by boat. References See also Caves of Scotland Show caves in the United Kingdom Sea caves Limestone caves Landforms of Sutherland Sites of Special Scientific Interest in North West Sutherland Protected areas of Highland (council area) Smoo Cave Landforms of Highland (council area) Scheduled Ancient Monuments in Highland Subterranean waterfalls