 The lake is drained into Manila Bay by the Pasig River, one of the most important rivers in the country due to its historical significance and because it runs through the center of Metro Manila.Located southwest of Laguna de Bay is Taal Lake, a crater lake containing the Taal Volcano, the smallest in the country.The environs of the lake form the upland Tagaytay Ridge, which was once part of a massive prehistoric volcano that covered the southern portion of the province of Cavite, Tagaytay City and the whole of Batangas province.