San Juan del Puerto was a Spanish Franciscan mission founded before 1587 on Fort George Island, near the mouth of the St. Johns River in what is now Jacksonville, Florida. It was founded to serve the Saturiwa, a Timucua tribe who lived around the mouth of the St. Johns. It was organized by separating them into nine smaller villages. It has an important place in the study of the Timucua, as the place where Francisco Pareja undertook his work on the Timucua language.