31 sites were surveyed on Mull. Further work is recommended, as Mull is a large area. The authors admit that algae, sponges, smaller crustacean and bryozoa in particular were under-recorded, with emphasis on mollusca. The area was divided into 3 parts for survey and assessment. North and west Mull was the richest for variety of habitats and species. Eastern Mull had least variety, with Ross of Mull in between. The authors suggest that eastern Mull has more affinities with the Firth of Lorne while north and west Mull are more Hebridean (?inner) in character. Asteria gibbosa was recorded from 5 stations in north-west Mull. An assessment of sites is given, bearing in mind the limitations of the survey:- Ross of Mull: Eiban Fheoir (Grade 2, possibly) - variety Loch Scridain Head (Grade 1) - wierd and interesting place; salinity varies and is a complex site. North and west Mull: Rubha Baile no h-Airde (Grade 1) - variety of pools and lagoons. Sound of Ulva (Grade 2) Calgary Bay and Rubha nan Oireau (Grade 2) Sgeir Dearg (Grade 2) - intertidal rock platforms. Calve Island - Doirlinn a Chailbhe (Grade 1) - Zostera bed and large bivalve molluscs. The authors consider that it would be of considerable importance to survey Ulva and Gometra. Site and species lists are appended, with abundances. The present survey was undertaken concurrent with a survey by divers, who concentrated on the north end of Mull and the Sound of Mull for logistic reasons - see R584 Bishop G.M. (1984). Records currently considered sensitive have been removed from this dataset.