Poonithura Sree Krishna Temple is steeped in mythology and history, offering insights into its name and the fort complex located there. The legend surrounding the creation of Lord Sree Poornathrayeesa stands out prominently. According to the Mahabharata, in the chapter of Santhana Gopalam, Arjuna is said to have constructed this temple for Lord Krishna. Further, Lord Vishnu tasked Arjuna and Lord Ganesha with a mission on Earth: to locate the missing Brahmin children from Vaikundam. After an extensive journey, they converged at a particular spot as evening approached. Arjuna aimed towards the east by taking an arrow from his "Pooni" (arrow container). He directed Lord Ganesha more that the location where the arrow landed should be ideal for their prayers and the chanting of Vishnu mantras. Following Arjuna's guidance, Lord Ganesha proceeded eastward and discovered the arrow embedded in a place surrounded by abundant sesame seeds near the Poorna River. This location, where Arjuna opened his "Pooni," came to be known as "Poonithura." The area chosen for their worship of Lord Maha Vishnu was named "Poorna Veda Puri," later renamed Tripoonithura. It was at this spot that Arjuna erected the Sree Poornathrayeesa Temple. Additionally, the name "Poonithura" can be interpreted as "Pooni," representing the containment for arrows, and "Thura," signifying a seashore.