Apo Reef lies in which Philippine strait?

Apo Reef lies in the Mindoro Strait.

The Mindoro Strait separates Mindoro Island from Busuanga Island and the Calamian Islands of Palawan. Apo Reef sits in the strait's western waters, off Occidental Mindoro, rather than on the main island's shoreline. The reef divides the waterway into the Apo East Pass and Apo West Pass.

This location helps explain Apo Reef's unusual geography. The reef is a broad, mostly submerged atoll-like formation with northern and southern lagoons separated by a deep channel. It lies roughly 28 kilometres west of Mindoro, while the nearest important mainland municipality is Sablayan. Three small surface features—Apo Island, Apo Menor, and Cayos del Bajo—help identify the reef in an otherwise open stretch of sea.

The strait itself connects the South China Sea with the Sulu Sea and is an important alternative shipping route between the Indian and Pacific oceans. It is easy to confuse the Mindoro Strait with nearby Philippine waterways such as the Tablas Strait or Surigao Strait, but neither contains Apo Reef. The reef's position in the Mindoro Strait is a defining geographic fact.