1. Use a powerful grappling hook to launch a long rope over and after security the rope climb across
2. Use small aircraft to take off from one side of the canyon to land on the other.
3. Take liberties with the term "cross the Grand Canyon" and use a car to drive around it
4. Climb down to the bottom of the canyon and hike back up the other side
5. Wait for a particularly heavy rain storm to fill the Grand Canyon and take a boat across.