Formal state law in California establishes beaches as open access. Surfers nonetheless overcome the obvious potential free-rider problem this creates and instead engage in time consuming activities to cooperate in beach protection. Utilizing ethnographic fieldwork and a game theory model, this study illustrates how the informal rules of surfing interact with formal state law to inadvertently facilitate collective action for environmental conservation by increasing the individual benefits for local surfers to organize against environmental threats. How and why some groups of surfers have managed to cooperate to protect surf breaks—an ostensibly open access common pool resource—illustrates how social groups more generally can overcome the collective action problem and self-organize to provide a non-excludable public good. Both fisheries and forests are de facto open access resources in many parts of the world, making the insights from this case study widely applicable to a diverse variety of important policy issues involving the management of natural resources and the provision of public goods absent state coercion.