2. in deep water. Also,
in over one's head. In trouble, with more difficulties than one can manage, as in
The business was in deep water after the president resigned, or
I'm afraid Bill got in over his head. These metaphoric expressions transfer the difficulties of being submerged to other problems. The first appears in Miles Coverdale's 1535 translation of the Book of Psalms (68:13): "I am come into deep waters." The second, which also can signify being involved with more than one can understand, dates from the 1600s. Also see
over one's head.