What Diane said... When standing at the bus turnaround out in front of the main buildings, just follow walkway, with general store/olivias on your left and hospitality/check-in on your right, proceed until you see water!! Then it is down a set of stairs by the pier.
Well, I would suggest that you ask where the Gurgling Suitcase is, order a pina colada or a margarita, relax on one of the picnic tables and within 20 minutes it will become obvious where the Trumbo Ferry pulls up!!
j