A diving survey of 36 sites; 16 in Loch Nevis, 19 in Loch Hourn and 1 in the Sound of Sleat. Sites are described briefly, and a species list given. The sublittoral topography was mainly of steep sediment slopes from mud to muddy sand and gravel. There are also extensive outcrops of bedrock, heavily silted unless in current. A distinct thermocline was present, with temperatures ranging from 9 degrees Centigrade at 50 m to a maximum of 16 degrees Centigrade at the surface. The range of species found reflects low energy, silt-dominated conditions; Nephrops and all 3 sea pens were found in mud. Neocrania and Protanthea were all characteristic of the otherwise barren bedrock, and Swiftia and Diazona were recorded nearer the mouth. Increased current resulted in large populations of Ophiothrix and Ophiocomina. Few red algae; undergrowth mostly brown species. Several nudibranchs of interest were recorded, and Leptometra celtica, Aureliania and Thyone roscovita. Records currently considered sensitive have been removed from this dataset.