come hell or high water
No matter what. In spite of any obstacle. I don't care if I have to drive through a blizzard—we are getting to this wedding come hell or high water!
hell or high water, come
Also, in spite of hell or high water . No matter what difficulty or obstacle, as in I'm going to finish this week, come hell or high water. This colloquial expression, alluding to the destructive forces of hellfire or flood, was first recorded in 1915 but is thought to be older.