Visitors who plan to venture outside of San Juan should plan to rent a car. This is by far the best way to explore the island. Most of the major American car-rental agencies have locations throughout the island, and there are several local agencies as well. For the most part, roads are well maintained and well marked. Gasoline is sold by the liter, speed limits are measured in miles per hour, and distance is measured in kilometers. And all road signs are in Spanish. International driving licenses are required for drivers from countries other than the United States.

Driving around San Juan can be bit nerve-racking for those not accustomed to inner-city driving. The sheer number of cars on the island guarantees congested roadways, so be sure to schedule extra time for road trips. Drivers tend to speed and don’t leave much space between cars. They also can be creative when it comes to navigating traffic—rolling through stops and driving on the shoulder of the highway is not uncommon. Ponce has, hands-down, the worst drivers. It’s practically a free-for-all, and they blow their car horns constantly.

Take extra precautions when driving in the mountains. Fortunately the traffic is light, but the roads are narrow and winding. Drivers who travel these roads every day tend to proceed at a perilously fast clip. If the driver behind you appears impatient or tailgates, pull over and let him pass. On roads with a lot of blind curves, it is common practice to blow the car horn to alert oncoming traffic you’re approaching. If it’s raining, beware of small mudslides and overflowing riverbanks, which sometimes close roads. And whatever you do, don’t look down! But really, it’s not as bad as it sounds. Driving through Puerto Rico’s majestic mountains is well worth a few shattered nerves.

There is an excellent, major, limited-access highway system—called Autopista—that dissects and nearly encircles the island, some of which are toll roads ($0.25–1.25 per toll). The speed limits range 50–65 miles per hour.

The rest of the island’s numbered roads are called carreteras, typically written as the abbreviation “carr.,” followed by a number, such as Carr. 193. Major carreteras often have spur routes that either go into a town’s center or along its beachfront. A road number followed by the letter “R” or the word “Ramal” indicates a spur route that goes through a town’s commercial district. Beachfront routes are often indicated by the abbreviation “Int.” or an addition of the numeral “3” after a road number.

Addresses are typically identified by road and kilometer numbers, for instance: Carr. 193, km 2. Look for the white numbered kilometer posts alongside the road to identify your location. In towns, streets are called avenida (abbreviated as Ave.) and calle.