A situation or circumstance that is foreign, unclear, or unfamiliar and which may be dangerous or difficult as a result. We're starting to get into unfamiliar waters exploiting these tax loopholes. If we aren't careful, the government may crack down on us hard! John has always kept himself closed off from family members, so his real feelings have been unfamiliar waters for all of us.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.