algae beach cliff coastline eroded erosion Great Britain hillside natural nature Pembrokeshire rocks sand sea seaweed shore united kingdom view wales water welsh blue coastal danger edge island rock summer surf wild calm cloud Cornish cornwall England english harbour Ives lighthouse ocean peaceful placid ripples saint sky St. Ives anchorage green moored Skomer yacht Balearic Islands boulders dangerous harsh majorca mediterranean rough rugged Spain spanish spray spume waves white coast gravel pattern pebble pebbles soak stone stones texture wet guard HDR horizon life Nyberg safety tower clouds sun sunset boulder low tide sandy