Whilst the 1" O.S. maps of Scotland show scattered caves all over the Highlands and around the coast, the ones of particular interest to speleologists are limited to a band of Cambrian limestone which outcrops in patches between Durness on the north coast and Strath Suardal on Skye.
At Durness the only large cave is Smoo Cave (N.G.R. 29/418672). Here the Allt Smoo falls down an open shaft just south of the main road and flows through a big chamber to the sea. A small branch passage contains a separate rising whose source has not yet been ascertained.
There are a number of shakeholes in the area just south of this, but the only other cave so far noted is a small series of chambers in the east bank of the Allt Acnaidh (29/388632). There is also a small sink at 29/373623, the water from which rises about 300 yards to the north west.
The next area southwards to have been investigated is Glen Traligill where a complex system of caves is found in Cnoc nan Uamh (29/276206). Although no tests have been made it appears probable that the water in these caves comes from sinks at 29/283193, 29/280198 and 29/277198 which together yield a substantial river. The Uamh an Tartair is the entrance to the upper part of the system which rises from a pool, proved by survey to lie under the Uamh Cailliche Peireag 250 yards to the south. Downstream the Waterslide, a cascade on a 30° slope, reaches, at a depth of 140 feet, a constriction and then an apparent sump, but a branch passage to the right bypasses this and leads to a very definite sump at 160 feet.
The sink at 29/277208 on the main Traligill stream appears to be a separate system and probably rises 200 yards downstream. It sinks again at the Lower Traligill Cave 29/270209 where it is probably joined by the Cnoc nan Uamh water. In dry weather this cave can be descended down a 30 slope to a depth of about 60 feet, but in wet weather it acts as a rising.
In normal weather there is a rising from a cave at 29/267213 but in dry weather the water does not reappear till below the waterfall at 29/264315, and a point 100 yards below this.
Uamh nan Caluman 29/258219 appears to be only a series of oxbow passages in the side of the gorge.
In the next valley south of Traligill, the Fuaran Allt nan Uamh 29/261178 is a very powerful rising but it does not give much promise of entry. The caves (29/268170) marked on the 1" map appear to be part of a big system but are now very solidly clay filled. Near the sink at 29/271163 is a small shaft and chamber in rather rotten rock. The most promising point in this valley is a hole about 100 yards below the waterfall at 29/275172. The narrow entrance in the north bank of the stream leads into an upper level of dry roomy passage which terminates in a heap of boulders which must lie somewhere near under the surface waterfall. The stream which passes under the main passage is probably the water sinking nearby and is last seen in a sump, but the bigger stream probably originates from a sink 300 yards above the waterfall. This latter rises from a pool but sinks amongst boulders which look like a promising dig.
In the Elphin area are the Uamh an Tartair 29/217092 and Uamh an Poll Eoghainn 29/205094. The first contains the bigger stream, the Abhainn a'Chnocain which can, in dry weather, be followed to a sump in a low passage; but in wet weather it backs up over 30 feet to the top of the first pitch.
Normally the stream reappears about half a mile NNE of the sink but in wet weather it rises again 100 yards east of the sink.
The Uamh an Poll Eoghainn has so far been descended 60 feet but it merits a dry weather visit since its water rises 350 feet lower down and threequarters of a mile to the north.
Near Loch Kishorn is a small cave at 18/860444. Although the entrance is through a deep pool on the west side of the stream, the cave is dry and does not extend far.
On Skye, a small pot has been noted at 18/595183.
Several of the other small outcrops of Cambrian limestone have been investigated but have not yielded anything of interest.