The origin of this tradition is unknown, with people believing that it may be related to the Moorish presence in the region from the 8th century until the 13th century.
Celebrated across the region, on 29 August, people leave their houses and bathe in the sea. The popular belief says that this bath would protect bathers from Demons. It would be common for people from the interior of the region to go to the sea and celebrate the Banho 29. The bath is believed to clean the souls of the people who would swim in the sea.
It is important to note that, besides those living in the Algarve, people from the interior would go to the beach, and most of them could not even swim.
In Aljezur, 29 August is a municipal bank holiday, with the swim happening, usually on Praia de Monte Clérigo. The beach is located nine kilometres away from Aljezur, but it is one of the most famous beaches in the municipality. During the bath, people, besides cleaning their souls, may find many sea species that will probably be around in the water.
In Lagos, the event usually happens next to Fort Ponta da Bandeira, where the Bensafrim River meets the Atlantic Ocean. It was, in the past, one of the most important fortifications in the region, being used for checking if the enemies were coming from the sea. Constructed in 1690, it was destroyed by the 1755 earthquake. The time passed and it became unsuitable for the defence of the territory, being abandoned until 1956, to serve as a naval branch of the Mocidade Portuguesa.
Vila Real de Santo António celebrates Banho 29, calling it a holy bath (banho santo), in Praia da Manta Rota, as part of the Festas de São João de Degola.
In most localities, the bath is taken at midnight, to mark the beginning of the 29th of August with a soul-cleaning bath. Usually, people do not wear the bikinis and bathing suits we are used to seeing, currently. People like to dress up as in the past. The bathing suits, for both men and women, will cover the legs, and normally, no one is shirtless. Night dresses may also be used to go to the beach, with some putting bonnets on, to protect their hair from the seawater. Men will probably wear white pants and sleeveless white shirts.
After a good night of sleep, people may go to the beach and enjoy a picnic with family and friends and enjoy the beach for a little more. Some locals even mention that until the end of September, the seawater will be blessed by São Miguel, being the greatest time of the year to swim at the beach and enjoy spiritual protection.