At the first corner take the right hand road, NOT THE TUNNEL. The road is a much easier and hence faster turn. After the first natural tunnel you go through you'll find a break in the guardrail on your right. Go though this break and continue straight across a beach (along the water) for this shortcut. After you re-enter from the beach, turn left, right, left and before you finish the next right you'll notice a break in the stone wall on your left (you should be able to see a lighthouse in front of you). Turn through the break and stay to the left on the grass so that you are running beside a stone wall. This will lead you to the end of the short cut.