The zooxanthellate coral, Porites panamensis, is one of the most common reef builders in the eastern Pacific. Field work and controlled experiments have shown that this species is remarkably resistant to extreme environmental conditions such as low salinity, low pH, and low omega aragonite. We report the presence of a population of P. panamensis living under anomalous conditions for a reef coral in the flow of a shallow hydrothermal vent system, with sediment temperatures higher than 50 °C, a pH below 7.5, and the continuous influence of water with abnormally high metal concentrations. The survival of this coral in this habitat might be due to the high genetic plasticity of both the host coral and its symbiont zooxanthellae.