The ferry from Puntarenas to Playa Naranjo makes 4 round trips daily. This pleasant trip, takes a little more than an hour and provides a delightful view of the Gulf of Nicoya and many islands (make sure to take the ferry to Playa Naranjo and not the one that goes to Paquera and leaves from the same dock).
From Playa Naranjo it is a short drive (9 Km) to Bahia Gigante. If you don't drive a car, you can get a private taxi service to Bahia Gigante.
In Bahia Gigante look for Rosío Gayoso: