Navigating the rush hour in Tokyo yesterday made me realise I could teach my son a Chinese idiom: 人山人海.
人山人海 (rén shān rén hǎi) literally means ‘people mountain people sea’.

Since the collocation ‘a sea of people’ exists in English, you can infer that the idiomatic meaning refers to a place teeming with people, a crowded place.

I’m keen to see if my son can recognise these Chinese characters. After all, 山 and 海 refer to the elements.

According to its entry in Baidu, it was first mentioned in a popular Chinese novel called 水浒传 (The Water Margin).

I guess a newly conceived term gains traction easily when it makes use of easily relatable elements in the first place. Now you know!