- Location: Situated in the southern part of the Western Ghats in India; extends across Kerala (Pathanamthitta, Kollam, and Thiruvananthapuram districts) and Tamil Nadu (Tirunelveli and Kanyakumari districts), forming a trans-state mountainous landscape of exceptional ecological value.
- Biosphere Reserve (India): Declared as a Biosphere Reserve by the Government of India in 2001 to conserve its unique biodiversity, endemic species, and fragile forest ecosystems while promoting sustainable development in surrounding communities.
- UNESCO Recognition: Designated as a UNESCO Biosphere Reserve in 2016 under the Man and the Biosphere (MAB) Programme, recognizing its global ecological importance and role within the Western Ghats biodiversity hotspot.
- Area: Encompasses a total area of approximately 3,500 km², divided into Core (~1,135 km²), Buffer (~1,445 km²), and Transition (~920 km²) zones; geographically distributed between Kerala (~1,828 km²) and Tamil Nadu (~1,672 km²).
- Protected Areas Incorporated: Includes major protected regions such as Shendurney Wildlife Sanctuary, Peppara Wildlife Sanctuary, Neyyar Wildlife Sanctuary, and the Kalakkad–Mundanthurai Tiger Reserve, forming a contiguous conservation network across the southern Western Ghats.
- Peak: Named after the prominent Agasthyamala (Agasthyamalai) Peak, rising to about 1,868 meters above sea level, which is among the highest peaks in the southern Western Ghats and holds both ecological and cultural importance.
- Ecological Significance: Functions as a crucial ecological corridor linking the high-altitude Western Ghats with the adjoining southern plains, facilitating wildlife movement and gene flow; forms an integral part of the globally recognized Western Ghats biodiversity hotspot.
- Rivers: Several important rivers originate from or flow through the reserve, including the Neyyar, Karamana, Shendurney, and Tamirabarani rivers, supporting agriculture, drinking water supply, and downstream ecosystems.
- Tribe: Predominantly inhabited by the Kani tribe, an indigenous community known for its traditional ecological knowledge and sustainable use of forest resources.
- Plants: Characterized by tropical evergreen forests, montane grasslands, wetlands, and rich biodiversity; notable for its abundance of medicinal plants, including Arogyapacha, as well as diverse orchids and numerous endemic plant species.
- Medicinal Plants: Widely renowned for its medicinal plant wealth, particularly species like Arogyapacha, the region is often described as the “cradle of traditional Indian medicine” due to its long-standing association with Ayurveda and indigenous healing systems.
- Animals: Supports diverse wildlife such as the Bengal Tiger, Asian Elephant, Lion-tailed Macaque, Nilgiri Langur, Malabar Trogon, Malabar Pit Viper, gaur, leopard, and several endemic amphibian and bird species characteristic of the Western Ghats.