The map was provided by the Federal Agency for Nature Conservation (BfN) delineating reef areas primarily located within the Natura 2000 sites "Sylter Outer Reef" and "Borkum-Reefground"(BfN 2004). The delineation was done by use of backscatter data, in-and epifauna sampling including underwater videos and scientific diving within different research projects coordinated by the Federal Agency since 1998.