Guanacaste is the fifth province of Costa Rica according to the geographical division established.
It is located in the northwest of the country. It limits at the north with Nicaragua, at the east with the province of Alajuela, at the south with the province of Puntarenas and at the west with the Pacific Ocean. Its extension make it the second largest province of the country, although it is also the most unpopulated.
The relief of the zone combines the volcanic summits of Guanacaste's mountain range with wide plains that open towards the Pacific. The Guanacaste Conservation Area (ACG) is located in this province, which is a World Heritage Site declared by Unesco in 1999.
In addition, there are two other protected areas, the Tempisque Conservation Area, which occupies the Nicova peninsula; and a sector of the Arenal-Tempisque Conservation Area, which occupies the southeast of the province.