in uncharted waters

In a situation or circumstance that is foreign, unclear, or unfamiliar and which may be dangerous or difficult as a result. We're in uncharted waters with these obscure tax loopholes. If we aren't careful, the government may crack down on us hard! The country is in uncharted waters now—we're facing a crisis unlike anything we've ever dealt with before. A: "This fool is clearly in uncharted waters running an entire company." B: "I know, he has no idea what he's doing."