There are plenty of great attractions for all the family in the Algarve, and one of the best days out overall is a trip to one of the many theme parks and aqua parks along the coast where you can either ride white knuckle roller coasters, or slide down suicidal looking slides into cool water and soak up the sun. A good theme park within driving distance of most resorts is the Krazyworld Park adjacent to the zoo in Algoz, and a good day out for the family.
Families with older children are better off heading to Slide and Splash close to Lagos, where there are plenty of rides for people who like their excitement a bit wetter.