An apparatus and a method for attenuating water pressure pulses generated during sea piling when a percussion mechanism is used, including the stage of driving at least one pile into an earth by a percussion mechanism, while along at least a part of its axial extension, the pile is surrounded by water and at least partly by a tubular outer sleeve; and at least one gas-filled space is provided between the inner periphery of the outer sleeve and the outer periphery of the pile. The apparatus includes mechanisms for providing the gas-filled space.