Aranmula Vallamkali, the water fiesta of Aranmula (10 kms from Chengannur and 16kms from Pathanamthitta) during Onam (September), owes its origin to the Sree Parthasarathy Temple situated on the banks of the Pamba river. The vallamkali, associated with the annual temple festival, is usually held on the last two days of the festival. The event that attracts tourists from all over the world, is conducted not to win any trophy or prize but to celebrate the anniversary of the Sri Krishna idol installation, the main diety at the Aranmula Parthasarathy temple. It is conducted in the Pamba River in front of the temple to commemorate the crossing of the river by Lord Krishna.

Around 39 to 41 palliyodams (snake-boats) participate in this colourful carnival. The Snake boats which resemble a snake with its hood raised, has a length of about 100 ft or 35 m, the rear portion towering to a height of about 20 ft. while the front tapers gradually. This boat can accommodate up to 120 people including oarsmen, singers and helmsmen. The oarsmen wear white dhotis and turbans. The occupants in the boat carry ornamental umbrellas of silk and gold.  The golden Aranmula Vallamkali, the water fiesta of Aranmula (10 kms from Chengannur and 16kms from Pathanamthitta) during Onam (September), owes its origin to the Sree Parthasarathy Temple situated on the banks of the Pamba river. The vallamkali, associated with the annual temple festivalornamental cloth fixed at the head of the boat, the flag and the colorful parasols at the center make it a spectacular show of pageantry too.

Offerings and prayers to Lord Krishna are held early in the morning on the day of the race as the snake boats assemble near the temple. The race is commenced in the afternoon and the boats take off in pairs to the rhythm of full throated singing and shouting. The participants row up and down the river to the tune of songs known as 'vanchipattu'. The occupants carry banners and decorated silk and gold umbrellas. After the water sport there is an elaborate feast in the Aranmula temple. Aranmula Vallamkali, organised under the sponsorship of Palliyoda Seva Sangam, is more of a water festival than a competition. For the past few years, the Central Tourism Ministry has been providing financial assistance for preserving and promoting this legendary snake boat race, believed to be in existence for the past 1,000 years.