Parque Nacional del Este (National Park of the East) is located in the La Romana Bayahibe area, which makes it easy to explore from Punta Cana. The park has been a national nature reserve since 1975, and features postcard-perfect beaches, lush tropical forest, a dry forest that was once the spiritual home of Taino Indians, and the famed Saona Island—one of the country's best diving locations, but also a notable beach bum chill zone. The small village of Mano Juan on Saona Island offers a glimpse at what life is like in rural Dominican Republic; most of the men here make their living as subsistence fishermen, though today tourism is the second-largest employer in the area.
The island is also home to an important turtle sanctuary; from March through November the critically endangered hawksbill turtle (alongside leatherbacks and greens) lands on the beaches to lay eggs. You can volunteer to work with local naturalists and biologists from the turtle sanctuary to collect eggs and deliver them to the turtle hatchery, where each little reptile will be given a slightly better chance at survival before being released back into the wild.