North of Liberia via the InterAmerican Highway, the Guanacaste National Park is an evergreen and cloud forest of roughly 700 sq. kilometers around the Orosi and Cacao volcanoes. Overall, the trails are not well-marked or heavily used.
Generally, the park is located about 37km north of Liberia on the InterAmerican Highway. However, none of the roads to the Biological Stations at the various trailheads are marked, especially the more popular Maritza Biological Station (supposedly across Highway 1 from the road leading west to Cuajiniquil about 47km north of Liberia).
The Volcan Cacao Trail is a strenuous 18km hike from the Maritza biological station to the Cacao summit. The exact route is not particularly well marked; make sure to used the reference book or get a good map. The route passes through both rainforest and cloud forest on the way to the summit. The trail starts behind the ranger house along an old roadway. About 100 meters from the house, you will pass an old gate and cross a field. After about 2km, there may be a sign for Sendero Casa Farm. Look for the trail heading uphill to the left. There will be a river crossing and some slick trail sections. At about 4km, there will be another sign for the farm; veer right on the trail. After reaching the Cacao Field Station, the summit is only another 2.5km beyond starting from behind the station.
Also starting from the Maritza biological station, there is the Llano de Los Indios trail which is a 3km route trip through forest and field. The trail leads to El Pedregal where there are almost 100 petroglyphs representing a pantheon of chiseled supernatural beings lie half-buried in the luxurious undergrowth that cloaks the mountains hide. The trail starts across the field from the dorms at the biological station (look for the gate in the fence to the right).
A 12km trail ascends to the Cacao Biological Station. It begins in Potrerillos, about 9km south of the Santa Rosa park entrance. From Potrerillos, head 7km east to Quebrada Grande (take the daily 3pm bus from Libreria), then 10km north along a 4WD road to the station. During the rainy season, you will have to park 5km before the station at Río Gangora. You can lodge in Mata de Caña in Quebrada Grande or directly explore the Cacao Biological Station grounds. There is a 900m trail called Pedregal which leads to an observatory for forest fires. You can also climb to the top of Volcán Cacao, a 3hr. Hard climb into the cloud forest that starts on the east side of the lab. You will need a permission slip.
The Guanacaste National Park is one of the most closely monitored parks scientifically, with three permanent biological stations, all of which offer basic accommodations. The Pitilla Biological Station is at 600 meters elevation on the northeast side of Cacao amid the lush, rain-soaked forest. It is reached via a rough dirt road from Santa Cecilia, 28 km east of Hwy. 1 beyond Hacienda Los Inocentes. A 4WD is essential. It's a nine-km drive via Esperanza. Do not blithely drive east from Santa Cecilia as that route goes to Upala. Ask locals for the correct route. Cacao Field Station (also called Mengo) sits at the edge of a cloud forest at 1,100 meters on the southwestern slope of Volcán Cacao. It has a laboratory and rustic dorms. You can get there by hiking or taking a horse 10 km along a rough dirt trail from Quebrada Grande (see Quebrada Grande, above); the turnoff from Hwy. 1 is at Potrerillos, nine km south of the Santa Rosa National Park turnoff. You ll see a sign for the station 500 meters beyond Dos Ríos (11 km beyond Quebrada Grande). The road--paved for the first four km--deteriorates gradually. Four-wheel-drive vehicles can make it to within 300 meters of the station in dry season, with permission; in wet season youll probably need to park at Gongora, about five km before Cacao (youll have to proceed on foot or horseback).
Maritza Field Station is farther north, at about 650 meters on the western side of the saddle between Cacao and Orosí Volcanoes. The vegetation here is dry and transitional dry-wet forest. You get there from InterAmerican Highway RUTA 1 via a dirt road to the right at the Cuajiniquil crossroads. The exact dirt road is very difficult to find since there are numerous dirt roads heading in roughly the right direction near this crossroads. None of the dirt roads are marked. If you do find the right road, it is 15km to Maritza. There are barbed-wire gates: simply close them behind you. Four-wheel drive is essential in wet season. The station has a research laboratory. From here you can hike to Cacao Biological Station.
Here are some basic notes on driving in Costa Rica for the tourist. There is a myth about the quality of the roads and of VW bus sized pot-holes. This may have been true years ago, but on the main routes, this is no longer true. With that said, there are still numerous challenges for first time drivers in Costa Rica. First, do not expect much out of so-call “highways”, like the InterAmerican Highway. The fancy name makes the uninitiated think this is a major 4 lane divided, restricted access road. Well, yes, about 1% is. The rest is two lane (marginally), undivided, rural roads with tons of traffic constantly stopping, turning, passing or driving slowly. Like every other road in the country, you can expect to see on the road numerous unexpected cows, cyclists, pedestrians, bus stops, school crossing zones, dogs, mud slides, police check points, unannounced one-lane bridges, missing manhole covers, and, of course, a never ending stream of semi-trucks driving erratically fast. What you do not find on any roads is much signage. There are infrequent signs indicating the distance to the next town, and even more infrequent are road names or numbers (if at all), including even within major towns. To make matters worse, signs that used to exist are disappearing due to deterioration or theft. Also, do not expect drivers to use their head lights, even in a heavy rain shower, unless it is really dark. This makes passing in rain a game of roulette since you can’t see the oncoming traffic. Speaking of dark, do not drive at night since the roads in some areas can be ruled by those under the influence of alcohol.
If you have to drive through San Jose, make sure to do it at dawn to avoid the horrendous traffic all day long, including weekends. Keep in mind several maps show highways passing through San Jose. This is not true. They end abruptly on the outskirts of town and you have to slug it out in a crazy stop-and-go traffic and many unmarked turns to get to the other side all day long. There are unsigned so-called by-pass routes around San Jose, but finding them can be a challenging game of trial-and-error, and they are only marginally better.
If you have to drive on the Nicoya Peninsula, you can expect to find generally better roads with better signage. However, there are numerous unmarked eroded road sides, especially over stream culverts. Do not drive at night. Watch out for the iguanas sprinting across the road.
A GPS unit can be helpful when navigating roads, however, the maps in Costa Rica were created using a special map datum. This datum is not usually available on GPS units but the road base maps were created with it. Therefore if you use the default WGS84 datum with a base road map on the GPS unit, you will always show a position being about 0.5 miles to the north of the road base map.
When picking up a rental car, make sure to check all the tires for wear, check the spare tire pressure, check the tire jack, and make sure to test the lock on the spare tire. It would be wise to quickly purchase a can of Fix-A-Flat.
Overall, Guanacaste National Park is the 9th most popular walking & backpacking of all 20 hiking in Costa Rica.