The Site comprises the western coast of Alderney and adjacent shallow waters and islets in the strongly tidal, high-energy system of the northern Channel Islands. It includes diverse and inter-related ecosystems, notably rocky shorelines, tide-swept habitats, kelp forest and coastal grassland. The rocky islets are very important for breeding birds; a large nesting population of northern gannets (Morus bassanus) is established on the Garden Rocks and Ortac with about 17,000 individuals. The Site also forms a regionally important breeding area and year-round refuge for a seal colony and dolphins. It hosts numerous species of marine algae; there are also sizeable areas of habitat associated with various life stages of finfish and shellfish, notably sandbars, kelp forest and intertidal rocky shore, which are used by multiple species for spawning and as a nursery. A land-use plan protects the terrestrial part of the Site, including its intertidal rock formations. Besides commercial and non-commercial fishing, tourism is the main activity. Additionally, a significant amount of research is conducted on this highly biodiverse Site, involving both local wildlife organizations and university research placements, including long-term monitoring and scientific research. The Site is threatened by climate change effects, invasive species, and human activity.