Distributed pressure sensing arrays fabricated from fiber Bragg gratings have been demonstrated for real-time monitoring of the dynamic subsurface pressures beneath water waves in a wave tank. Two sensing arrays were used to monitor horizontal and vertical pressures in the tank as periodic wave trains passed overhead. The horizontal and vertical arrays contained 90 and 35 sensing elements, respectively, spaced at 1-cm intervals allowing highly accurate spatial resolution to be achieved in both orientations. The wave tank paddle was programmed to generate wave-trains varying from ~5- to 30-cm peak-to-trough and the pressures measured using the fiber optic array were validated using commercial piezo-electric pressure sensors and video image analysis. The length and sensor separation of the fiber optic sensing array can be varied to suit the location under test, and the fiber optic elements make the devices inherently resistant to corrosion and electromagnetic interference.