The Cagayan River, also known as the Río Grande de Cagayán, is the longest river and the largest river by discharge volume of water in the Philippines. It has a total length of approximately 505 kilometres (314 mi) and a drainage basin covering 27,753 square kilometres (10,715 sq mi). It is located in the Cagayan Valley region in northeastern part of Luzon Island and traverses the provinces of Nueva Vizcaya, Quirino, Isabela and Cagayan.
Cagayan Valley, designated as Region II, is an administrative region in the Philippines, located in the northeastern section of Luzon Island. It is composed of five Philippine provinces: Batanes, Cagayan, Isabela, Nueva Vizcaya, and Quirino. The region hosts four chartered cities of Cauayan, Ilagan, Santiago, and Tuguegarao.
Isabela, officially the Province of Isabela is the second largest province in the Philippines in land area located in the Cagayan Valley region in Luzon. Its capital and largest local government unit is the city of Ilagan. It is bordered by the provinces of Cagayan to the north, Kalinga to the northwest, Mountain Province to the central-west, Ifugao and Nueva Vizcaya to the southwest, Quirino and Aurora to the south, and the Philippine Sea to the east.
Ilagan, officially known as the City of Ilagan, is a 1st class component city and capital of the province of Isabela, Philippines. According to the 2020 census, it has a population of 158,218 people making it the most populous city in the province. It holds the title as the most number of voters in the province with 98,565 electorates. Ilagan was a first class municipality before it became a city.
Palanan, officially the Municipality of Palanan, is a 1st class municipality in the province of Isabela, Philippines. According to the 2020 census, it has a population of 17,684 people.
Alicia, officially the Municipality of Alicia, is a 1st class municipality in the province of Isabela, Philippines. According to the 2020 census, it has a population of 73,874 people.
Divilacan, officially the Municipality of Divilacan, is a 2nd class municipality in the province of Isabela, Philippines. According to the 2020 census, it has a population of 5,827 people.
Gamu, officially the Municipality of Gamu, is a 4th class municipality in the province of Isabela, Philippines. According to the 2020 census, it has a population of 30,655 people.
Mallig, officially the Municipality of Mallig, is a landlocked 4th class municipality in the province of Isabela, Philippines. The municipality has a land area of 133.40 square kilometers or 51.51 square miles which constitutes 1.07% of Isabela's total area. Its population as determined by the 2015 Census was 32,208. This represented 1.91% of the total population of Isabela province, or 0.88% of the overall population of the Cagayan Valley region. Based on these figures, the population density is computed at 228 inhabitants per square kilometer or 591 inhabitants per square mile. of people.
San Mariano, officially the Municipality of San Mariano, is a 1st class municipality in the province of Isabela, Philippines. According to the 2020 census, it has a population of 60,124 people.
San Mateo , officially the Municipality of San Mateo, is a 1st class municipality in the province of Isabela, Philippines. According to the 2020 census, it has a population of 66,663 people.
Tumauini, officially the Municipality of Tumauini, is a 1st class municipality in the province of Isabela, Philippines. According to the 2020 census, it has a population of 70,743 people.
Magat Dam is a large rock-fill dam in the island of Luzon in the Philippines. The dam is located along the Magat River, a major tributary of Cagayan River. The construction of the dam started in 1975 and was completed in 1982. It is one of the largest dams in the Philippines. It is a multi-purpose dam which is used primarily for irrigating about 85,000 hectares of agricultural lands, flood control, and power generation through the Magat Hydroelectric Power Plant.
Fuyot Springs National Park is a protected area of the Philippines located in the mountain slopes of Barangay Santa Victoria in Ilagan City, Isabela, 405 kilometers northeast from Manila. The park, which also contains the Ilagan Sanctuary, is 819 hectares in area and extends to the nearby municipality of Tumauini. It was established in 1938 through Proclamation No. 327.
The Gaddang are a linguistically-identified ethnic group resident for centuries in the watershed of the Cagayan River in Northern Luzon, Philippines. Gaddang speakers were recently reported to number as many as 30,000. This number may not include another 6,000 related Ga'dang speakers and other isolated linguistic-groups whose vocabulary is more than 75% identical.
The Peñablanca Protected Landscape and Seascape is a protected area and national park in Peñablanca, Cagayan. It is on the border with Isabela province, contiguous with the Northern Sierra Madre Natural Park. The protected area, best known as the location of Callao Cave, covers the largest block of forest under conservation in the province. It covers 118,781.582 hectares of the northern Sierra Madre mountain range and its adjacent Pacific coast.
The Northern Sierra Madre Natural Park is the largest protected area of the Philippines covering the northern range of the Sierra Madre mountains of eastern Luzon. The park is located in the eastern part of the province of Isabela in Cagayan Valley containing a total of 359,486 hectares. It was first declared a wilderness reserve encompassing an area within a 45 kilometres (28 mi) radius of Palanan Point known as the Palanan Wilderness Area through Letter of Instructions No. 917-A signed by President Ferdinand Marcos on 7 September 1979. On 10 March 1997, the area was converted into a natural park with the signing of Proclamation No. 978 by President Fidel Ramos.
The Sierra Madre is the longest mountain range in the Philippines. Spanning over 540 kilometers (340 mi), it runs from the province of Cagayan down to the province of Quezon, forming a north–south direction on the eastern portion of Luzon, the largest island of the archipelago. It is bordered by the Pacific Ocean to the east, Cagayan Valley to the northwest, Central Luzon to the midwest, and Calabarzon to the southwest. Some communities east of the mountain range, along the coast, are less developed and so remote that they could only be accessed by taking a plane or a boat.
Tuguegarao, officially known as the City of Tuguegarao, is a 3rd class component city and capital of the province of Cagayan, Philippines. According to the 2020 census, it has a population of 166,334 people, making it the most populous city in Cagayan Valley and Northeastern Luzon.
The Quirino Protected Landscape is a protected area in the Philippine island of Luzon that covers a large portion of the province of Quirino. It was established in 2004 to preserve the watershed area containing the headwaters of the Cagayan River, also known as the Rio Grande de Cagayan, which supports major irrigation systems in the entire Cagayan Valley region. From an initial area of 206,875.41 hectares, the protected area now forms a total aggregate area of 175,943.62 hectares divided into three parcels after a 2005 amendment opened up a few areas to mining. It is a key biodiversity area of the Sierra Madre Biodiversity Corridor.
