The route, officially La Ruta Panorámica Luiz Muñoz Marín after the first elected governor of Puerto Rico, is really an interlocking network of around forty different rural highways, so you should follow the small brown “Ruta” signs throughout – these can be unreliable, however, so invest in a detailed atlas or map of the island. You’ll need two or three days to see everything, and longer if you intend to stop for some hiking along the way.
On the east coast, the road begins as a loop between Yabucoa and Maunabo, incorporating scenic coastal highway PR-901. From Yabucoa, PR-182, a narrow road that rarely sees much traffic, takes you into the mountains, and eventually, via PR-181 and PR-7740, into the Bosque Estatal de Carite.
Despite their somewhat hazardous reputation, driving the twisty roads up in the mountains is far less dangerous than the speeding highways of San Juan, assuming you stay within the fairly slow speed limits (usually 35mph), and take your time. All the roads are paved but heavy rain can cause problems, and there are some traffic black-spots around Aibonito. Places to stay are usually off the main route, and it’s worth booking ahead as rooms are limited, though you should have no trouble finding petrol stations. Note that to camp in any of the forests, you’ll need to get permits in advance from the DRNA in San Juan.