Luzon Coast

Luzon is the largest island in the Philippines and the most populous, but its coastlines — spanning the South China Sea to the west, the Philippine Sea to the east, and the Sibuyan and Verde Island Passage to the south — hold a range of very different marine environments. The tidal signal varies by coast and by the bathymetry of the adjacent sea. On the South China Sea side (Ilocos Coast, La Union, Bataan), the pattern is mixed semidiurnal with spring range typically 0.8 to 1.2 metres at the PAGASA gauge stations along the northwest coast. On the Philippine Sea side and in Verde Island Passage south of Batangas, the semidiurnal signal is stronger, with spring ranges at Legaspi (Albay Gulf) reaching 1.2 to 1.8 metres. PAGASA operates the authoritative tide gauges for the Philippines including the principal Luzon stations at Manila Bay and Legaspi. Verde Island Passage between Batangas and Oriental Mindoro is described by marine biologists as containing the highest documented marine biodiversity of any comparable body of water on Earth — the nutrient upwellings and tidal exchange in the passage support the densest known concentration of marine species. Manila Bay, enclosed on three sides, modifies the tidal signal inside it; the bay entrance at Corregidor Island is the reference point for tidal exchange. The Luzon coastline is heavily affected by typhoons from July through November, with the western (Pacific-facing) coast of Quezon and Bicol receiving direct typhoon landfall more frequently than the sheltered Ilocos and La Union coasts.