Oiapoque lives in the the Brazilian popular culture as the end of their long coastline, starting in Chuí.
From French Guiana:
When entering or leaving Brazil, do not forget to visit the Federal Police to get your passport stamped. (Boat drivers may tell you otherwise; don't listen to them!) Police stations are located downtown (intersection of Av Barão do Rio Branco and R Noberto Pennafort) and on the bridge. The police station downtown is open everyday 8am-12pm and 2-6pm. By car you can pass immigration on both sides when crossing the bridge. It is open Mondays to Fridays 8am-12pm and 2-6pm, and Saturdays 8am-12pm.
The main square is being refurbished, restaurants, bars, and clubs have been temporarily relocated on the out-skirt of the city, meaning that a taxi ride is needed to reach it from down town where most of hotels are.