Summary Estimated observations of the biotope AB.A1G4 and AB.M1G4 were collected from the Baltic Sea area by expert judgements for HELCOM Red List of biotopes, habitats and biotope complexes. Description Baltic aphotic rock and boulders or mixed hard and soft substrates dominated by soft corals (Alcyonacea)The HELCOM Red List of Baltic Sea underwater biotopes, habitats and biotope complexes (2013) is an updated and improved version of the Red List assessment of marine and coastal biotopes and biotope complexes published in 1998. The classification of the report follows the proposed International Union for Conservation of Nature (IUCN) criteria and assessment principals but with some modifications for the Baltic Sea.Altogether, the HELCOM Underwater Biotope and habitat classification (HELCOM HUB) includes 209 biotopes of which 59 were red-listed. Many of the red-listed biotopes are located in deep areas of the Baltic Sea due to oxygen-free nature as well as in the southwestern Baltic Sea due to the salinity restricted distribution of species in certain biotope. The HELCOM assessment relies heavily on expert judgment and inference, and the questionnaire data represents the estimated presence-absence data not in-situ measured data. This must be taken in account when observing the map presentation. The biotopes are shown on the map using the EEA 100 km grid. This dataset displays estimated presence of AB.A1G4 and AB.M1G4 according to HELCOM RED LIST assessment experts:The biotopes occur in the Kattegat and Belt Sea on rocky substrates in exposed areas of high salinity. The distribution map indicates the area in the 100 x 100 km grid where biotopes are estimated to occur based on environmental gradients and the availability of the specific substrate.(Data (expert judgements) collected in HELCOM RED LIST project, released in May 2013)