Sentence:  A man, whom we had noticed walking rather uncertainly, as if not sure whether he was going up or down hill, at this crisis came to a pause, staggered off the <WSD>boardwalk</WSD>, and leaned against the fence. 
Meaning of the word marked with <WSD> tags:  A slightly elevated path for pedestrians over sandy or swampy ground, typically made out of wood; specifically  one running alongside a body of water or beach.