In a land area of 3,642 square kilometers, the diocesan territory covers the entire civil province of Zambales and Olongapo City. It remains a suffragan of San Fernando, Pampanga, and its titular patron is St. Augustine whose feast is celebrated August 28.
Zambales is subdivided into 13 municipalities (Subic, Castillejos, San Marcelino, San Antonio, San Narciso, San Felipe, Cabangan, Botolan, Iba, Palauig, Masinloc, Candelaria, and Santa Cruz) and 1 city with 1st and 2nd districts (shared with Olongapo City).
Olongapo City is a highly urbanized city and administers itself autonomously from the province. Panatag Shoal (Scarborough Shoal) a Philippine-claimed Exclusive Economic Zone (EEZ), is a designated part of the province. Olongapo City is politically subdivided into 17 barangays.
Both belongs to Region III or most known as Central Luzon.
As of 2016, the total population of the diocese is 788,130.
Suffragan of San Fernando, Pampanga
Created Prelature: June 12, 1955
Erected: Oct. 18, 1955
Elevated to Diocese: Nov. 15, 1982
Comprises the province of Zambales and Olongapo City
Titular: St. Augustine, August 28.
Iba was created a prelature nullius on June 12, 1955, and on Nov. 15, 1982 was elevated to a diocese. Before its creation into a prelature Iba, in the province of Zambales, was part of the Diocese of San Fernando, Pampanga and that of Lingayen-Dagupan in Pangasinan. Diocesan priests from the Diocese of San Fernando served in Olongapo, Subic, Castillejos, San Marcelino and San Antonio in Zambales, while diocesan priests from Lingayen-Dagupan served in Masinloc, Candelaria and Sta. Cruz.
Binabayani Festival (November 30)
Binabayani Festival is celebrated during last week of November where it re-enacts the battle between Christians and Aetas through a dance interpretation happening in the town of Masinloc and the activity is featured in the town plaza. The dance is complemented with Aetas costume; people’s bodies all rubbed with charcoal and are naked waist up with short pants and bird’s nest-made hats all in black color. Props include bamboo drums and bolos for their weapons while the Christian accessories include white pants and polo shirts with colored band up from the shoulder down to the waist. They, too, have props of bolos and bamboo drums.
Domorokdok Festival (Sambal word for Dance) is a grand celebration that brings all Botoleños together in unity and cooperation, in pursuit of peaceful and progressive Botolan. This is usually done on the 4th day of May. It brings back the memory and the tradition of merriment that has long been forgotten for so many decades. Domorokdok is a Zambales term for dance. The festival became a tradition in Botolan. Almost all barangay fiestas featured the dance as part of the day’s festivities. Through the dance, old folks express their thanksgiving for the blessing they received.
The "Fiesta Poon Bato," (literal translation is Feast of the Sacred Stone) held in January, is a religious festival that attracts over half a million people each year. The festival venerates Ina Poon Bato also known as Nuestra Senora de la Paz y Buen Viaje (Our Lady of Peace and Good Voyage), the oldest known image of the Virgin Mother in Asia. The Barrio of Poon Bato located in the Botolan, that is host to the image and the fiesta, was completely destroyed during the 1991 Mt. Pinatubo eruption. The icon was saved and moved, along with the barrio inhabitants, to nearby Loob Bunga Resettlement Area.
The "Mango Festival" is held in the provincial capital of Iba every April.
The Sibit-Sibit Festival is an annual event held in Olongapo to depict the rich and colorful history of the City. Sibit-Sibit is a word derived from the erstwhile saga of Ulo ng Apo which connotes the small paddle used for fishing as Olongapo was ultimately born from being one of the ancient fishing villages of the country. During olden fiestas, fishermen held banca races using sibit sibit driven by human strength in the quest to win races.