Get to the 8th or 9th checkpoint, or where you need to do the large jump over the seemingly bottomless pit. Get down onto the ramp, then slowly drive over the ramp, trying to keep against the wall. A large vent should fall out to serve as a ramp, facing backwards. Use the backwards momentum to coast along the ground and you'll find a cardboard box located near the back wall.
So far, nothing is known about the origin or purpose of the cardboard box. There appear to be some blue ink stains on the box. Redlynx has recently announced to offer a unique price to the winner of the Blue's riddle contest: "the mystery box that's in the game"!
This section is reserved for Confirmation/comments about this investigation. Investigations will remain open until advised by Redlynx that the final solution for each secret is found.