The Centre d'Interpretació is the practical starting point for Serra d'Irta Natural Park, the rugged coastal strip that keeps Peñíscola from being only castle, beach, and promenade. The centre explains the park's geology, plants, tracks, and protected coastline before you head out into the scrub and coves.
It is worth a stop if you plan to hike, cycle, or drive the rougher coastal routes south of town. Ask about trail conditions and seasonal restrictions, then use the visit as a bridge from the busy old town to the much wilder side of the peninsula.