In a news story today I saw this quote: "“It is very unusual, even over a period of 40 years, to see such a sea of change in public attitudes."
Actually the phrase, courtesy of Shakespeare, is sea change (without the "of"):
sea change - noun
1. a striking change, as in appearance, often for the better.
2. any major transformation or alteration.
3. a transformation brought about by the sea
Coined by Shakespeare, in Ariel's song, "Full Fathom Five," in The Tempest (1611)