As seen in the Philippine map, San Ildefonso is the most prominent peninsula found in the island of Luzon. By definition, a peninsula is an elongated piece of land jutting out into the sea from another piece of land in a coastal town or village. This geographical formation is a safe haven for ships and small vessels during storms and typhoons. It is also known as Cape San Ildefonso amongst the locals of Casiguran. Small communities in this peninsula can be found in Brgy. Busok-busok, Sitio Pasaruboy and Sitio Dalugan.
