The Parco Regionale encompasses, over 50 000ha, the limestone Velino (2 487m) and Sirente massifs (2 348m), separated by the high plateau of Le Rocche and through which the Aterno River runs. On the list of remarkable natural sites, Aielli-Celano gorge, one of the largest canyons in the Apennines, and the Sirente crater (Cratere del Sirente), a 140m-diameter circular lake feature near the top. The Subequana Valley, which crosses the park, has a fine necropolis.