What do I do in this corridor across the chasm?

Hint 1 of 6:

If you explore that corridor, you'll find a slight indentation in the floor
and ceiling.

Hint 2 of 6:

Save, then step in it.

Hint 3 of 6:

Well now, aren't you glad you saved?

Hint 4 of 6:

Try to trigger the trap, and still live to tell about it.

Hint 5 of 6:

Step into the edge of the indentation.