David

You can fall off me, I flow, I sound like crash, crash ,crash, I can be dangerous, I am very fast. What am I?

The oblong light house, ruby and cream, motion less by the dunes. The flavor of salt lingers on in you mouth, while you sit still on the dunes. The smell of fish wafts through the air, while you sit still on the dunes. The whistling wind sings a little song, while you sit still on the dunes. You feel calm and relaxed, while you sit still on the dunes. The touquise sky is fully clear, while you sit still on the dunes. The crashing waves drown out all sound, while you sit still on the dunes. The grainy sand is everwhere, while you sit still on the dunes. The day goes by much peacefully, while you sit still by the dunes.

I am a box, I rhyme with hurdle, I hide inside when I'm scared, I can be a pet. What am I?