There is hourly bus service between Santiago and both Valparaíso and Viña del Mar. Tur-Bus, Pullman, and other companies leave from Santiago's Terminal Alameda, or take buses from metro station Pajaritos and avoid most of the capital’s traffic. Smaller companies serving the other beach resorts depart from Santiago's Terminal Santiago.
To get to nearby Reñaca or Concón you can take a micro or liebre (local bus) from Viña del Mar, or from Valparaíso to get to Laguna Verde. But your best bet for getting to the smaller beach towns farther north or south of the twin cities is from Valparaíso’s bus terminal. Plan ahead, as the buses may fill up, especially in summer.