Coamo lies about twenty kilometers inland on the southeastern part of the island. The name of Coamo is derived from an Indian word meaning extensive flatlands. Its founding dates back to 1579, making it one of the older towns on the island after San Juan and San Germán. It was because of the interest on the part of Friar Diego de Salamanca, that permission was granted to him to establish a church in Coamo to provide the residents of that area in the basic religious services. The town’s original name was San Blas de Illescas. By 1582, there were twenty families living in Coamo, in the same area where the Tainos had had their village of Guayama.
Friar Diego de Salamanca founded the hermitage of San Blas and lived there until 1618 aided by the economical support of the families of the town. The church in 1616 was made of brick and thatch, and its architecture had the simple characteristic lines of the construction done on the island.
Coamo is famous for its thermal springs. They are noted for their healing and therapeutic waters. Long before the Spaniards arrived on the island, the Indians bathed in these waters, and according to legend, this was the fountain of youth that the Indians spoke to Ponce de León about which he mistakenly went to search for in Florida, and unfortunately for him the search would end in his death.