The Western Ghats or Sahyadri mountains run along the western edge of the Deccan Plateau, and separate the plateau from a narrow coastal strip along the Arabian Sea. The range starts from the river valley of the river Tapi near the Gujarat border, and then runs through the states of Maharashtra, Karnataka, Kerala, and Tamil Nadu, almost to the southern tip of peninsular India. The average elevation is around 900 meters, with the highest point at Anai Mudi at 2695 meters height. Distinctive features include the Nilgiri Hills (Tamil Nadu), and the only major gap in the range, the Palghat Gap, which joins Tamil Nadu to Kerala.

The largest city within the mountains is the city of Pune, in Maharashtra, on the eastern edge of the range.

The mountains intercept the rainbearing monsoon winds, and form an important watershed for peninsular India. They are well forested; in the south they contain the only rain forests of southern India. These forests are increasingly threatened, and are the home of some very interesting fauna and flora, many of them showing affinities to South-East Asia. Many of these faunal and floral elements are not found anywhere else in the Indian region except in parts of the North East of India. Several national parks lie within the range.

The Western Ghats are also home to many endemic species and the endemism is very great in the amphibian and reptilian fauna. The snake family Uropeltidae is almost entirely restricted to and diversified in this region of the world. The frog Nasikabatrachus sahyadrensis was discovered in 2003 as being a living fossil.

The area is hilly in certain parts with numerous streams, waterfalls and the forests help to nourish many perennial rivers in South India including the Godavari River, Krishna River, and Kaveri River.