From the airport head north...It is the only direction you can go. Stay on the main road and you will go through the main business district of Zihuatanejo, there are several lights and it is quite busy just stay with the main flow of traffic headed north. You will go up a big hill. At the top of the hill go right following the sign that says "Lazaro Cardenas"... do not go towards Ixtapa.
Now you are on the main (and only) road North bound. There are several interchanges that lead down to some of the smaller towns just keep going in the main direction...following the signs that say "Lazaro Cardenas". After about 30 minutes you will see the turn off for Troncones (It is very obvious). Go left and take the road all the way to the beach (1.5 mi.). The road ends at the beach. Go right and stay on the dirt road for about 5 or 10 minutes.....when you pass "Hacienda Eden" we are just about five more houses up on the left. There is a big wood gate with a sign that says "La Marea". It is easier than it may sound.