In-sea seismic energy sources, deployed at or near the seabed, generate seismic waves in earth formations beneath the seabed when activated by a triggering mechanism at a precise time synchronized with seismic data acquisition by sensors deployed at predetermined locations around a well drilled for oil and gas exploration. Seismic waves generated at the seabed travel with more direct and predictable ray-paths through the earth to the sensors. Acquired data, including a precise time and location of the seismic events, are used to provide enhanced borehole and sea-bottom seismic surveys.