Thiruvananthapuram, also known as Trivandrum, is the capital city of the Indian state of Kerala. It is located on the southwest coast of India, bordered by the Arabian Sea to the west and the Western Ghats to the east. 

The city covers an area of approximately 214 square kilometers and is situated at an altitude of 10 meters above sea level. The city is divided into three main geographical regions - the low-lying coastal plains, the midland region, and the highland region. 

The coastal plains of Thiruvananthapuram are narrow and stretch for about 16 km along the Arabian Sea. This region is characterized by sandy beaches, estuaries, and backwaters, and is home to several fishing villages. 

The midland region is a narrow strip of land that lies between the coastal plains and the Western Ghats. This region is characterized by gently undulating hills and valleys, and is mainly used for agriculture. 

The highland region of Thiruvananthapuram is situated in the eastern part of the city and is characterized by steep hills and dense forests. The Western Ghats, which run parallel to the coast, form a natural barrier to the east of the city and are an important source of water for the region. 

The city is crossed by several rivers, including the Karamana River, the Killi River, and the Vamanapuram River. The Neyyar River, which originates in the Western Ghats, flows through the city and is an important source of water for the region.