According to sacred lore, Vilwamangalam Swamiyar, a mystic devoted to Lord Mahavishnu, once beheld a divine child assisting him in worship. When the child suddenly vanished, a heavenly voice guided the sage to a dense forest named Ananthankadu. There he witnessed the cosmic vision of Lord Anantha Padmanabha reclining upon the celestial serpent Adi-Śeṣa.
Offering the humble “manga in naranga” (tender mango in coconut shell), Swamiyar consecrated this sacred grove. From that moment, the spot became the abode of Sree Nagaraja—King of Serpents—and is believed to be the spiritual cradle of the famous Sree Padmanabhaswamy Temple.
The presiding deity is Sri Anantha Nagaraja, revered as an eternal manifestation of Lord Vishnu. Devotees also worship Mahalakshmi, Ganapathi, Naga Lakshmi, Naga Kanyaka, Dhanwanthari, Hanuman, Sastha, Saraswathy, and Mahakali. The temple is renowned for relieving Naga Dosha, infertility issues, and ailments related to serpent deities.
Major celebrations occur in the Malayalam months of Edavam and Karkkadakam. Key offerings include Sarpa Bali, Aslesha Bali, Naga Mandala Pooja, and Kalamezhuthum Pattum. Devotees throng the temple for blessings of prosperity, good health, and family harmony.
The temple stands inside the historic Fort area of Thiruvananthapuram, a short walk northwest of Sree Padmanabhaswamy Temple. Pilgrims believe that circumambulating the temple and making offerings of milk, turmeric, and tender coconut water appease the serpent gods and remove obstacles in life.