The Daily Post challenge is at: https://dailypost.wordpress.com/photo-challenges/narrow/
One of the narrowest places I have ever been to is Lower Antelope Canyon near Page, AZ. Walking through it, in many spots only one person at a time could pass through. The following photos attest to that.
This last photo was a surprise for me. I first heard the bird or birds chirping, and when I saw one I quickly took a shot before it flew away. If you can recognize what kind of bird it was, please let me know in a comment.