from Naples, take the SS 7 Appia until Formia/Gatea, and then the Via Flacca until Terracina, where you can take the SS 148 Mediana (stretch Terracina-Latina of the SS 148 Pontina) diverting at the junction to Sabaudia on the SP Migliara 53 which goes through the Forest of the Park up to the town of Sabaudia.

from the North or the South, take the A2 highway in the direction of Naples or Rome, exit Frosinone, and then follow the SS 156 Monti Lepini in the direction of Latina up to the junction to Priverno; from here, if you take the SP Marittima you can reach, following the indications for Sabaudia and crossing the SS 7 Appia, the SP Migliara 53 which, after the crossroads with the SS 148 Mediana (stretch Latina-Terracina of the SS 148 Pontina), crosses the Forest of the Park up to the town of Sabaudia.

By train
with the Roma-Napoli line via Formia, using the trains stopping at the FS station of Priverno-Fossanova, where the bus line CO.TRA.L for Sabaudia leaves;

By bus
from the station CO.TRA.L. Metro/Bus Eur Laurentina in Roma, by taking the direct bus line or those changing in Latina, in the direction of Sabaudia;

By plane
if you arrive by plane at the airports in Roma (Ciampino and Fiumicino), you can take the metro connections FS/CO.TRA.L. to get to Roma Termini (FS) or to EUR Laurentina (Metro Line B CO.TRA.L.), and then go ahead by train+bus as mentioned above.