What’s the origin of the phrase ‘Clear blue water’?
The rowing reference is first cited in the 23rd July 1870, edition of The Boston Advertiser in a piece titled ‘Yale & Harvard Boat Racing’:
“Lyman promptly set forty-four strokes to the minute, which brought them to the stake with an oar’s length of clear water between their boat’s stern and the Yale’s bow.”
In the contemporary allusive sense it was first used either by or about the British Conservative Party and their opponents in the early 1990s.