Fascinating! I love history. Was there a land bridge to Isla Ixtapa?

Not that I'm aware of.

...Capitán Álvaro de Saavedra y Cerón weighed anchor in the Bahía de Zihuatanejo and set sail for the Philippines in two ships and a tender that Hernán Cortés put at the disposition of the Spanish King Carlos V in order to settle a land possession dispute between Spain and Portugal: Florida, Espíritu Santo, and Santiago respectively. I believe part of the dispute was over Portuguese colonies in the Mollucas, which was part of the discussions that lead to the Treaty of Zaragoza in 1529.

October 31, 1527 is the day when the small bay of Zihuatanejo became an official sea port, and the first ships from the American Continent set sail for the Far East on the other side of the Pacific. Only one ship, Florida, arrived to Tidore in the Philippines five months after leaving Zihuatanejo. The other two ships went down with all hands soon after leaving port.

Capitán Saavedra y Cerón died attempting to return back across the Pacific, and it wasn't until 38 years later that another intrepid Spanish seaman and monk, Andrés de Urdaneta, correctly navigated the return trip from the Philippines and arrived in the Bahía de Santa Lucía in Acapulco.

Today Zihuatanejo remembers and honors our link to maritime history: the first successful crossing of the Pacific Ocean from the Americas to the Far East. At the naval memorial obelisk near the pier there is a plaque commemorating this historic event.