The invention relates to a device for dumping material onto an underwater bottom or installation, such as a pipeline. The device comprises a vessel, provided with a fall pipe through which the material is dumped on the underwater bottom; a steering device adapted to control the motion of the fall pipe relative to the underwater bottom; first monitoring means adapted to monitor the state of the underwater bottom; second monitoring means adapted to monitor the position of the steering device; and computing means adapted to compute, control signals for moving the steering device. The invention also relates to a method for dumping material onto an underwater bottom or installation.