To get to Algarrobo, the most common is to do it by car or bus from Santiago, the capital of Chile.
From Santiago de Chile you can take Route 78 to the south, and then Route 68 that leads directly to the city of Algarrobo, which is about 100 km west of Santiago.
There are also buses that leave from the Santiago Bus Terminal and connect with Algarrobo and other nearby cities on the coast.
See more about how to get to Algarrobo
See also information on Santiago de Chile.