South of the Central Luzon plains lies the largest inland freshwater lake in Southeast Asia, the Laguna de Bay. To the east of the lake is a plain that stretches westward to the Manila Bay. Large rivers from bays and mountain springs traverse the plain. In the northern part of the region, that is, Manila and Rizal, most of the plain had been converted into cities and towns, and are thus industrialized. Lying east of the lake is the southern terminus of the Sierra Madre mountain range at northern Quezon province.