The century-old festival in Yehliu, held to mark the end of the lunar new year holiday, is the only one of its kind in Taiwan and aims to bring peace and prosperity to the fishing village.
But what for decades was a small local festival now attracts visitors from around the island and abroad to complete the 500-metre ritual swim.
This year 130 people took part, including over 30 from around the world, from Russia and India to Brazil.
"I love being a sedan chair carrier -- the ritual has always brought us peace the whole year," local resident Fang Ze-hung, 20, told AFP.
More From This Section
"So many people wanted to do it this year that we had to register with the temple authorities three weeks in advance."
The chair carriers danced around a square outside the village's "Paoan Kung" (Peace Blessing Temple) with thundering firecrackers attached to the statues creating a haze of smoke as gongs and horns played traditional music.
The final harbour jump saw the eight sedan chair teams take a leap before walking across burning coals on the harbourside to finish the ritual.
American Michael Regraff said he had come along because he loved "traditional things" -- local authorities say the ritual is over 100 years old.
For others, plunging into the freezing water was an investment in the year ahead.
"I feel that joining this kind of ritual will bring me peace and prosperity," he said.