brown-water navy

noun3

1. •
   A naval force capable of military operations in riverine and coastal environments.

   • Gunboats and other vessels with shallow drafts that could navigate inland waterways were part of the Civil War's brown-water navies. — 2005
2. •
   A naval force capable of military operations only in inland waters.
3. •
   The portion of a naval force that is optimized for riverine operations.