it takes between 10 and 20 minutes to cross the bay, and the fare varies depending on the water route chosen.  

the ferry to charitas is the boat that arrives closest to the parque, and on this link is the schedule from praça xv, the ferry station from where all boats to niterói depart.

for visitors coming to niterói from rio de janeiro via boat, the easiest place where to find a taxi and arrange for a ride back would be at the ferry station called Estação Hidroviária de Charitas, located on  Avenida Prefeito Silvio Picanço, Jurujuba, Niterói (the continuation of  Avenida Quintino Bocaiúva.