San Mateo is a district of the San Mateo canton, in the Alajuela province of Costa Rica. San Mateo has an area of 64.85 km² and an elevation of 254 metres. It is located in the coastal lowlands near the central Pacific coast, 31 kilometers east of Caldera Port, 44 kilometers southwest of the provincial capital city of Alajuela and 53 kilometers from the national …San Mateo is a district of the San Mateo canton, in the Alajuela province of Costa Rica. San Mateo has an area of 64.85 km² and an elevation of 254 metres. It is located in the coastal lowlands near the central Pacific coast, 31 kilometers east of Caldera Port, 44 kilometers southwest of the provincial capital city of Alajuela and 53 kilometers from the national capital city of San Jose.