Romeria de San Roque (San Roque Pilgrimage)
One of Tenerife's most picturesque traditional pilgrimages: locals in colourful Canarian folk costume parade decorated ox-carts and rondalla music through the old town down to the sea, honouring Saint Roque. Free to watch, easy for visitors to enjoy with no Spanish needed.
Every 16 August, Garachico turns out to thank Saint Roque, the saint people once called on against the plague that swept the town in the 17th century. The thanks take a cheerful form. Ox-carts decked with greenery and flowers creak through the old streets, men and women turn out in proper Canarian dress, and rondalla bands keep the whole thing moving with strings and singing. The route runs from the Plaza del Muelle Viejo, by the harbour, up to the saint's little chapel.
It costs nothing to watch and you don't need a word of Spanish to follow along; the carts, the costumes and the singing carry the day on their own. There's plenty leading up to it, too. The week before brings a Fiesta de las Tradiciones, and the evening before the romeria itself there's a mass followed by fireworks.
Source: https://www.holaislascanarias.com/eventos/tenerife/romeria-de-san-roque/