Los Baños is one of the 30 Local Government Units of the province of Laguna. The town of Los Baños lies between the shore of Laguna de Bay (the biggest lake in the Philippines) and the legendary Mt. Makiling. It has a bearing of 14º 11’ North (longitude) and 121º 15’ East (latitude). It is situated about 63 kilometers away from Manila, the capital of the Philippines, and is bounded on the East by Laguna de Bay, on the South by Sto. Tomas, Batangas; on the West by Calamba, Laguna and Laguna Lake on the North.
The municipality has a total land area of 5,650 hectares which corresponds to 3.21% of the total land area of the province of Laguna. It is composed of 14 barangays and 85 sitios/purok. Barangays are classified into two: Urban areas – Batong Malake, Baybayin, and Timugan; Rural areas – Anos, Bagong Silang, Bambang, Bayog, Lalakay, Maahas, Malinta, Mayondon, San Antonio, Tadlac, Tuntungin-Putho. Based on NSCB Res. No. 9 Series of 2003, a barangay is classified as urban, if it has a population size of 5,000 or more, if it has at least one establishment with a minimum of 100 employees and if a barangay has 5 or more establishments with a minimum of 10 employees, and 5 or more facilities within the two-kilometer radius from the barangay hall.
The shape of Los Baños resembles the back of a fist. Its habitable area rests on the narrow southern shoreline of Laguna Lake and northern foothills of Mt. Makiling. Mount Makiling, with an elevation of 1,090 meters (3,633 ft.) above sea level, dominates the whole town and is traversed by five rivers, namely: Dampalit, Saran, Pili, Mulawin and Maitim, which all drain to Laguna Lake.
Another prominent feature at the northwest tip of the town is the Alligator Lake in Brgy. Tadlac. The lake, contained in a raised circular shape with a diameter of about 330 meters (1,100 ft.), is believed to be the mouth of an extinct volcano that juts out of Laguna Lake. The lake’s water level is higher than that of Laguna Lake.