From either of the Mexcaltitán [1] road’s-end embarcaderos, boat workers ferry you across (about $1 pp for colectivo, $5 for private boat, each way) to Mexcaltitán island-village, some of whose inhabitants have never crossed the channel to the mainland. The town itself is not unlike many Mexican small towns, except more tranquil, because of the absence of motor vehicles.
Mexcaltitán is prepared for visitors, however. Instituto Nacional de Arqueología y Historia (INAH) has put together an excellent museum (10 a.m.–2 p.m. and 4–7 p.m. Tues.–Sun.), with several rooms of artifacts, photos, paintings, and maps describing the cultural regions of pre-Columbian Mexico. The displays climax at the museum’s centerpiece exhibit, which tells the story of the Aztecs’ epic migration to the Valley of Mexico from legendary Aztlán, now believed by experts to be present-day Mexcaltitán.
Outside, the proud village church (step inside and admire the heroic St. Peter above the altar) and city hall preside over the central plaza, from which the town streets radiate to the broad lagoon that surrounds the town.
At the watery lagoon-ends of the streets, village men set out in the late afternoon in canoes and boats for the open-ocean fishing grounds where, as night falls and kerosene lanterns are used, they attract shrimp into their nets. Occasionally during the rainy season water floods the town, and folks must navigate the streets as Venice-style canals.
Links:
[1] http://www.moon.com/destinations/puerto-vallarta/the-nayarit-coast/san-blas-and-vicinity/mexcaltitan