céng​jīng​cāng​hǎi​nán​wéi​shuǐ

seen it all

  1. once
    previously; in the past; indicates that an action has happened before, often used in combination with guo
  2. the sea
    the deep blue sea; the vast ocean
  3. hard to do
    (bound form) Difficult to perform, manage, or achieve.
  4. water
    water; a liquid, juice, or lotion