Abstract: A device comprising a body; at least one propulsion unit fixed to the body and configured for moving the device along a sea bed; a collection unit having an inlet opening and a fluid channel extending from the inlet opening; a transport pipe fluidly connected to the fluid channel; and a fluid conveyance unit arranged in connection with the fluid channel and/or the transport pipe and configured to generate a fluid flow from the inlet opening to the transport pipe. There is also provided a method for removing sea floor sediments below a fish farm and a method for sea bed harvesting.