architecture barrier defence defensive engineering England english flood gray Great Britain grey hood landmark London protection river steel thames tidal tide water blue cloud exercise farm fence footpath gate green iron landscape sky summer Sussex track trail trailhead walk white anxious back beware danger guard look back lookout mammal meerkat on-guard rodent sit sitting surikat uneasy watch watch out watching worried worry boat carrier coast dinghy estuary fun leisure outdoors pleasure shore sport trailer view wheels yacht coastal coastline forest high hill hills madeira mist misty natural nature ocean panorama sea top village villages bay calm cliffs cove entrance Gairloch grass highlands inlet promontory Redpoint rock rocky scotland scottish shelter steep waves