deep water

/dipˈwɔtər/
adjective
  1. Relating to or occurring in deep parts of an ocean, sea, or lake.
    • The company specializes in deep-water oil drilling.
    • Scientists explored a deep-water trench using a special submarine.
    • Deep-water fish like tuna are often found far from shore.
  2. Involving or dealing with serious, complex, or risky matters.
    • The politician found himself in deep-water trouble after the scandal broke.
    • She knew the deep-water questions about ethics would be hard to answer.
    • Starting a business without a plan can get you into deep-water financial problems.
Synonyms
What does "deep water" mean? | whatsthatwordmean | whatsthatwordmean