unnavigable

/ʌnˈnævɪɡəbəl/
adjective
  1. Not deep, wide, or safe enough for ships or boats to travel through.
    • Many early explorers had to abandon their boats when they reached unnavigable rapids.
    • The river became unnavigable after the drought lowered the water level.
    • The canal was unnavigable due to fallen trees and debris.
  2. Impossible to travel through or across; not passable.
    • The dense jungle terrain was nearly unnavigable on foot.
    • After the storm, the roads were unnavigable because of flooding.
    • The app warned drivers that the mountain pass was unnavigable in winter.
Antonyms
What does "unnavigable" mean? | whatsthatwordmean | whatsthatwordmean