San Marcos is a town in the Mexican state of Guerrero.

Culturally and ethnically, the town and the municipality belong to what is known in Mexico as the Costa Chica (small coast) of Guerrero and Oaxaca.

This is a 125 km long region along the Pacific coast; it begins south of Acapulco and ends near the town of Puerto Ángel in the neighbouring state of Oaxaca.

The town is located approximately 59 km south of Acapulco.

However, the town already existed, firstly under the name of Xolutla and later La Estancia.