be in deep water

To be in a dangerous, vulnerable, or troublesome situation or position, especially that which could be beyond one's abilities to resolve. Anthony is in deep water with his creditors. If he doesn't pay off his debts, they're going to take everything he owns. I think I'm in deep water with this course—I don't know how I'll be able to catch up with all the work! I'm in deep water, Dave. I gambled away our mortgage money at the casino—what am I going to do?