2003 Natural England (NE) Plymouth Sound European Marine Site Sublittoral Monitoring dataset https://portal.medin.org.uk/portal/start.php?tpc=010_a0f31a4efa7c1b517bec3db7962a6a1d Plymouth Sound and Estuaries in South Devon was nominated as a candidate Special Area of Conservation (cSAC) to the European Commission in 1996 for the wide range of marine communities this group of large, shallow inlets and estuaries contains. The southwest location results in a species rich, southerly flora and fauna whilst the variations in wave exposure, water depth, rock and sediment types, salinity and tidal streams have produced a rich diversity of habitats within a small geographical area. This survey was designed to look at the extent and diversity of the biotopes on the subtidal reefs within the Plymouth Sound section of this European marine site. One of the main features of the area is the deep water channel which runs through part of this area which has steep, tide-swept limestone sides with kelp forests and faunal turfs. Elsewhere there are kelp forests with the southern kelp species Laminaria ochroleuca, cobble and pebble beds with ephemeral algae, and circalittoral shale bedrock with species-rich faunal turf including sea fans and sponges. This survey was commissioned to look at the extent and diversity of the infralittoral and circalittoral biotopes within the site and to initiate a repeatable monitoring programme, against which the condition of the site can be measured in the future. It forms part of a larger programme to monitor specific features of all the sublittoral marine SACs in England. This project was designed to enable the condition of the Plymouth Sound cSAC to be assessed against the targets for the features listed in the table below. This required diving fieldwork to establish a baseline of information against which the site condition could be assessed in the future and which could also be used in a comparison with extant data sets. The methods used broadly followed those outlined in the Procedural Guidelines in the Marine Monitoring Handbook (Davies et al. 2001). Fieldwork was carried out during 2003, with the data collected establishing a quantitative baseline of information for the site. Comparisons were made between these data and other data from various surveys since 1985, including quantitative data from monitoring trials carried out in 1998 and 1999. 20040101