#one would think 海象 is short for 海洋氣象 or 海洋現象 or something but it seems to really be its own word

[xiangqiankua]

So I was out and about and saw this

本區域海象不佳，自行車道路封閉，接近海岸線請注意安全

「海象不佳」 I suspected was something about the averse condition of the sea, but the only entry in Pleco was not what I was expecting, so I turned to the internet...

No, the beach was not overrun by aggressive walruses (although it would have made a good story, and 海象 is the term for walrus, albeit not in this context). 海象, according to the 全國法規資料庫, refers to 「潮汐、波浪及其他存在於大氣與海洋交界面之自然現象」, that is, tides, waves, and other natural phenomenon occurring where the atmosphere and ocean meet. Even used on a government website (is "Safe See" a pun or a typo though...):

The lesson here is to be reasonably skeptical and never put all your faith in google translate (or pleco) when there are clearly no large, angry marine mammals around.