Cerro Verde National Park is the visitor-friendly face of the larger Los Volcanes complex, a cool cloud-forest saddle between some of El Salvador's most dramatic volcanic scenery. The park itself sits on the extinct Cerro Verde cone, but most travellers come because it is the jumping-off point for Santa Ana Volcano, Izalco Volcano, and views down to Lake Coatepeque.
It is an easy day trip from Santa Ana, and a good one. The air is cooler than in the lowlands, the forest around the visitor area is full of birds, and the viewpoints give you that classic Salvadoran composition of black volcanic cone, green slopes, and blue crater lake.
Do not treat the volcano hikes casually. Santa Ana is the standard climb, but it is usually done in ranger-led groups and can close for weather or volcanic activity. Izalco is rougher, steeper, and more exposed. If you only want a gentle visit, stay with the Cerro Verde Cloud Forest Trail and the viewpoints around the visitor centre.