there are several different and interesting options to get to niterói easily from rio - and all are quite scenic.

there is a ferry that shuttles passengers between rio and niterói that's a pleasant and affordable trip.

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

the ferry to charitas is the boat that arrives closest to the area in niterói where there are the most hills - and on this link is the schedule from praça xv in the center of rio.