Pitch Lake at La Brea, about 30 kilometres west of San Fernando, is the largest natural deposit of asphalt in the world — roughly 100 acres of black, semi-solid bitumen that has been oozing up from underground for thousands of years. It looks like a vast, improbable parking lot, and walking across its surface (guided tours are obligatory) is an experience that is hard to describe to anyone who hasn't done it.
The lake is still actively mined, and the surface is in constant slow motion — old bicycle wheels and tree trunks gradually emerge from the depths over decades. Scientists have found unique microbial species living in the asphaltenes, making it a site of genuine research interest as well as a geological curiosity. There is a small museum on site. La Brea is easily reached from San Fernando by car or maxi-taxi, making it the obvious day excursion from the city.