a dangerous sink hole (madeira, portugal)

foam tourism blue erosion creek canyon sink hole rock cave vacation landscape water landmark travel touristic rocky nature madeira swimming not swim waves sea vulcanic rocks scenic suction effect dangerous danger beach natural coastline island shore north wild coast porto moniz atlantic ocean portugal stone pool piscinas naturais velhas foam tourism blue erosion creek canyon hole rock cave vacation landscape water sink landmark travel touristic rocky madeira swimming swim nature waves sea rocks scenic effect suction danger beach natural coastline island shore coast moniz ocean wild portugal pool