The Virgin of the Cuevita festival takes place between 15th and 30th August, with up to 25,000 people expected to attend. This festival is in Artenara and there are concerts.
Photo by Wwilliamm
The festival begins tonight at 7pm, when there is a mass at San Matias church nearby and the statue of the virgin is lowered into the little cave. Most of the festivities are in the evenings and tourists can mingle with local people to celebrate this fiesta.
Here is some information about Artenara: http://www.canario.co.uk/artenara.htm
Photo by Fitopaldi
The place is near Tamadaba, the pine forest, and you can check the bus timetable for the number 18 bus here: http://www.globalsu.net/es/lineas.php
Alternately you can rent a car in Gran Canaria and explore the whole island on your holiday.