to be in a place that you can clearly see:

I spent all morning looking for the book, and it was right under my nose the whole time.

She shoved the letter under her boss’s nose ( = made certain he saw it).

I had searched and searched for my path, and finally found that it was the one directly under my nose that I was used to.

He was just about to catch her when she doubled back, directly under his nose.

Well, I was just on my way home from school, looking at my feet while I was walking, when suddenly a piece of paper is shoved under my nose.