A device (100) comprising a body (7)； at least one propulsion unit (4a, 4b) fixed to the body (7) and configured for moving the device along a sea bed (101)； a collection unit (5, 5a-d) having an inlet opening (106) and a fluid channel (107) extending from the inlet opening (106)；a transport pipe (3) fluidly connected to the fluid channel (107)； and a fluid conveyance unit (6) arranged in connection with the fluid channel (107) and/or the transport pipe (3) and configured to generate a fluid flow (12) from the inlet opening (106) to the transport pipe (3). There is also provided a method for removing sea floor sediments below a fish farm (200) and a method for sea bed harvesting.
