We were just down in March and did NOT drive the entire spine. I hiked the spine from the East End to the highest point (about 2.5 miles from the villa---mainly uphill on the way out) on Jost and back. I did not go down into Great Harbour or onto the West End. Saving that for my trip this summer!

The road (if you want to call it that) over the top (at its highest point) is grass covered and had many rocks throughout. We have never driven over the top of the spine out of respect for the rental vehicle and its owners. <img src="http://www.traveltalkonline.com/forums/images/graemlins/Yikes.gif" alt="" />