San Martín Zapotitlán is a small municipality located in the department of Retalhuleu in Guatemala. Covering a land area of 24 km², it holds the distinction of being the smallest municipality within Retalhuleu and one of the smallest municipalities in all of Guatemala.
Despite its small size, the municipality is ranked among the top 50 most important municipalities in Guatemala due to the presence of three inaugurated amusement parks. Additionally, residents observe a small fair every November 11 to commemorate Martin of Tours.