List of reef(s) in Norway (found 6 locations). Category description: A surface-navigation hazard composed of consolidated materialSigurdskallen (Sogn og Fjordane) Sildegrunnen (Aust-Agder) Silhausen (Nord-Trøndelag) Silskallen (Troms) Sirinesskallen (Nordland) Sistafalla (Nord-Trøndelag)