Solid Hardwood, Engineered and Laminate Flooring - problems in sub floor

I have a plywood sub floor that has a hump in it about 5' away from the wall. when I took a level to it I found about a 1" differance from the top of the hump to the base board. I was told I could double or triple the cloud walk underlayment or can I use plywood at the low spot. or would you just recomend going back with carpet which I hate to do. any help you can give me would be greatly appriecated.

I had a similar dilema. A telepost had been raised in the basement in a recently purchased house that I was renovating. No clear idea why and how long ago so I did not want to risk lowering the post and cracking walls etc. I took an orbital sander and shaved off the hump to the joist flooring. Went down about 1 in. in doing so and nailed my unfinished hardwood onto the joists (perpendicular to HW direction fortunately). The area shaved was about 2' X 3' and I have had no trouble with it. Might be a better way but nothing came to mind so...

Remove the decking and cut down the high joist ot beam, and replace the decking plywood.

Or do as Jake suggests, only if it is ¾" hardwood your using.