If spelunking is one of your favorite pastimes, you will be thrilled with Smoo Cave. The largest sea cave in all of Britain, this natural wonder contains beautiful pools hidden deep within the caverns. It also holds the distinction in the United Kingdom as a combined fresh water and sea cave, with the water of the first chamber being supplied by the sea and inner chambers being freshwater. The fresh water comes from rain dissolving the carbonate dolostones.
There are three sections to the cave. Upon entering, spelunkers will step into a large main cavern. From there, an impressive waterfall chamber boasts a 20 metre (66 ft) waterfall cascading down from the Allt Smog stream above ground. The water from the stream filters in through the porous dolostones that surround much of the cave. Branching off from the waterfall area is a short freshwater passage. Boat tours are available during summer months, carrying passengers into the inner chamber to view the majestic waterfall from the surface of the water.