人山人海 How Do you say ,"Lots of people"?
True story 真实故事
I remember when I first came to China I tried to prepare myself for culture shock.Most importantly, I tried to prepare myself to so many people.When I arrived at the train station，a Chinese man from the university greeted me，and pointing all the people around me said，“Look，it is people mountain people sea”which was a direct translation.Unfortunately, this is not how we say it in English.
我记得当我第一次来中国时，已经做好了面临文化冲突的准备。最重要的是要努力让自己适应这么多的人。当我到达火车站时，一位中国大学生向我问好，然后他指着周围的人说:"Look, it is people mountain people sea.(看，人山人海)”显然，这是对中文的直译，只是在英语中我们不这样说。
If you want to use a "water" analogy to describe“人山人海”and still say it in a native way, you could say,“It's like/as though there is a sea of people.”
teeming with people—出现大量的人
swarming with people—挤满了人