人山人海[rén shān rén hǎi] 基本解释：

a large crowd

新英汉大词典：

人山人海  [rén shān rén hǎi]

• • - huge crowds of people; a sea of people [faces]; the sea of humanity (in a crowd):

    • a bumper audience;

      观众人山人海

    • The square was a sea of people.

      广场上人山人海。