Parque Nacional Portobelo is a vast marine and rain-forest reserve contiguous with Chagres National Park that protects both natural and cultural treasures. It extends from the cloud forest atop 3,212-foot Cerro Brujo down to offshore islands and coral reefs, and comprises the bay and fortresses of Portobelo. It holds an array of ecosystems and a wealth of biodiversity that ranges from nurse sharks and sea turtles along the coast to toucans and spider monkeys in the mountains. There is no proper park entrance, but you can explore the rain forest and mangrove estuaries along the coast on hiking or boat trips from Portobelo.
You can't miss the remains of the three Spanish fortresses that once guarded Portobelo Bay. The first is Fuerte Santiago de la Gloria, which is on the left as you arrive at the bay. It has about a dozen cannons and sturdy battlements that were built out of blocks of coral, which were cut from the platform reefs that line the coast. Coral was more abundant and
easier to cut than the igneous rock found inland, so the Spaniards used it for most construction in Portobelo.
Portobelo's largest and most impressive fort is Fuerte San Jerónimo, at the end of the bay. Surrounded by the "modern" town, it was built in the 1600s but was destroyed by Vernon and rebuilt to its current state in 1758. Its large interior courtyard was once a parade ground, but it's now the venue for annual celebrations such as New Year's, Carnaval, the Festival de Diablos y Congos (shortly after Carnaval), and the town's patron saint's day (March 20).
Fuerte San Fernando, across the bay from Fuerte Santiago, consists of two battlements—one near the water and one on the hill above. The upper fortress affords a great view of the bay and is a good place to see birds because of the surrounding forest.
Local boatmen who dock their boats next to Fuerte Santiago or Fuerte San Jerónimo can take you across the bay to explore Fuerte San Fernando for a few dollars. They also offer tours to local beaches, or a trip into the estuary at the end of the bay, which is a good place to see birds.