Indra, The king of the devas, needed flowers from earth to perform a shiva pooja at his abode. The deva-kanniyar (maidens) who were sent to earth to bring flowers, arrived at Thoonganai Maadam. When they saw the deity of this place, they were engulfed with joy. They stayed here worshipping the Shiva Linga instead of returning to their celestial abode.
Indira sent his divine cow Kamadenu to fetch them back. Kamadenu too joined the maidens in their worship, and did not return to Indra-loka. Perplexed, Indra then sent his white elephant Iravadham in search of the two parties who had not returned from earth. Iravadham found them worshiping God Shiva and he too decided to join them. Finally, Indra himself came down to earth and saw everyone worshiping a Shiva Linga and he too joined them. Later they all returned together to the celestial world with the blessings of God Shiva.
The name of this place “Pennakadam” is believed to have originated from this legend. “Penn” means maiden, “Aa” means cow (Kamadenu) and “Kada” means elephant (Iravadham).
A great flood, known as pralaya, once engulfed the entire world, leaving only one place untouched by the deluge: Pennadagam. Recognizing this, the Devas, or celestial gods, beseeched God Shiva to safeguard all living beings by preserving this sanctuary. In response, God Shiva commanded His Nandhi to ensure that the floodwaters could not penetrate the boundaries of Pennadagam. Nandhi, the sacred bull who typically faces the deity, turned in the opposite direction, effectively swallowing the oncoming floodwaters and preventing the submersion of the sacred site. Hence, the deity of this temple is also known as "Pralaya Kaleswarar". To this day, Nandhi is facing the entrance of the temple, continuing his vigilance.
A Chola King, who was an ardent devotee of Lord shiva, wanted to come to this temple. A heavy flood in river vellaru prevented him from reaching the temple. Undeterred, the king stood on the shore and fervently prayed to Lord Shiva for a way to behold his beloved deity. Moved by the king's devotion, Lord Shiva decided to elevate Himself to a higher position, so that the king could get a glimpse of Him from the shore. As a result of this divine intervention, the ground beneath rose significantly. Even today, an elevated portion of 30 meters, known as 'Kattu Malai koil' is within the temple premises. Situated on this elevated terrain is the Soundareshwarar temple, which can only be reached by ascending a series of steps.
This is the birth place of Kalikamba nayanar (one of the 63 Nayanmars) and his wife. Kalikamba Nayanar and his wife practiced "Pada Pujai," which involved washing the feet of Shiva devotees before offering them food. Once, his wife was reluctant to perform 'pada pooja' for a devotee who happened to be their servant. In a fit of rage, Kalikambar chopped off the hands of his wife for refusing to perform a divine duty. Pleased with Kalikambar's dutifulness, Lord Shiva restored his wife’s hands and blessed both of them. Hence the lord here is also praised as “Sri Kaivazhangeesar” – (The one who gave the hand).
The flagstaff (dwajasthambam or kodimaram), customary sacrificial altar (bali peedam) , and a nandi mandapam can be seen on entering the gateway of the temple. A 5 tier tower (rajagopuram) stands after. The presiding deity Sudarkozhundeesar is a Swayambhu Linga. The sanctum has three slotted windows on three sides which facilitates the devotees to see the deity from all sides.
When Tirunavukkarasar came to thoonganai maadam, he was remorseful of his affiliation to jainism for a time. He felt impure due to the long association he had with the Jains and their beliefs. He earnestly prayed to Lord Shiva and sang a pathikam seeking redemption to his mind and body. As soon as he finished singing the pathikam a goblin appeared before Tirunavukkarasar and untainted him by tatooing the symbols of shaivisam - Trident and Nandi on his shoulders. This miraculous incident which occured in the life of Tirunavukkarasar happenned at Thoonganai Maadam.