Altitude "Above or Below" a Sphere

Imagine a ribbon that runs completely around the Earth's equator flat against the ground. You cut the ribbon and tie in another piece of ribbon that is 710 inches long. That increases the total length of the ribbon by a bit more than the length of a bus. Now imagine that the ribbon is lifted at all points simultaneously, so that it floats above the Earth at the same height all along its length. What is the largest thing that could fit underneath the ribbon?