unwalkable
/ˌʌnˈwɔːkəbəl/Definitions
1. adjective
Not able to be walked on; impassable or difficult to walk on.
“The dense forest was considered unwalkable due to the thick underbrush.”
2. noun
A place that is difficult or impossible to walk in, especially due to being too dense or steep.
“The trail became an unwalkable mess after the heavy rain.”