caves cliffs coastline danger natural nature Pembrokeshire rocks sea shore stone wales water welsh barrel Cacti cactus defence defense ornamental plant pointed Prickly sharp spines spiny xerophyte Athabasca canada current dangerous fierce flow forest hazard landscape rapids river background caution construction lens light orange reflector safety texture traffic urban warn warning cave cavern cliff tide waves advice alert announcement appropriate-behavior appropriate-behaviour be-careful beware black care careful cars communicating communication concern directional directions informing lanes left lefthand-lane Look looking lookout message observant risk risks road road-rules sign signs traffic-flow vehicles watch watch-out white anger angry boot finger forgive hurt kill pain pinch punish punishment unforgiving Apulia chalk Gargano horizon Italy Puglia ahead arrow attention colorful coloring colors colourful colouring colours communicate curve curves curvy difficult driving irregular irregularity journey line outdoors risky roadsign roadway slow-down speed symbol transportation travel turn turning turns winding yellow architecture bay coast landmark lighthouse security tower