A system for determining a dynamic virtual representation of at least part of an environment that is navigable by a ship, the system having: at least one beacon (101, 102, 201, 202, 301, 302, 401-403) remote from the ship, each of the at least one beacon comprising: at least one sensor (101a, 102a, 201a, 202a, 301a, 302a, 411-415) for sensing surroundings information representative of a topography of at least part of the environment, a transmitter (101b, 102b, 201b, 202b, 301b, 302b, 420), and a controller (101c, 102c, 201c, 202c, 301c, 302c, 430) connected to the at least one sensor and configured to cause the surroundings information to be transmitted via the transmitter; and a control centre remote from the ship, the control centre comprising: a receiver configured to receive the surroundings information, a control unit connected to the receiver and configured to determine a dynamic virtual representation of at least part of the environment based on the surroundings information, wherein the dynamic virtual representation comprises a topographical map; and a transmitter connected to the control unit, wherein the control unit is configured to determine navigation information for use in assisting navigation of the ship based on the virtual representation, and the control unit is configured to cause the navigation information to be transmitted by the transmitter of the control centre to the ship; wherein the navigation information comprises course heading information, wherein the control unit is configured to generate an instruction to sense the surroundings information representative of at least part of the environment, wherein the control unit is configured to cause the transmitter of the control centre to transmit the instruction, and wherein the beacon comprises a receiver configured to receive the instruction, wherein the beacon comprises one or more manoeuvring units for controlling movement of the beacon in water, and wherein the controller of the beacon is connected to the receiver of the beacon and is configured to control the one or more manoeuvring units based on the instruction. at least one beacon (101, 102, 201, 202, 301, 302, 401-403) remote from the ship, each of the at least one beacon comprising: at least one sensor (101a, 102a, 201a, 202a, 301a, 302a, 411-415) for sensing surroundings information representative of a topography of at least part of the environment, a transmitter (101b, 102b, 201b, 202b, 301b, 302b, 420), and a controller (101c, 102c, 201c, 202c, 301c, 302c, 430) connected to the at least one sensor and configured to cause the surroundings information to be transmitted via the transmitter; and at least one sensor (101a, 102a, 201a, 202a, 301a, 302a, 411-415) for sensing surroundings information representative of a topography of at least part of the environment, a transmitter (101b, 102b, 201b, 202b, 301b, 302b, 420), and a controller (101c, 102c, 201c, 202c, 301c, 302c, 430) connected to the at least one sensor and configured to cause the surroundings information to be transmitted via the transmitter; and a control centre remote from the ship, the control centre comprising: a receiver configured to receive the surroundings information, a control unit connected to the receiver and configured to determine a dynamic virtual representation of at least part of the environment based on the surroundings information, wherein the dynamic virtual representation comprises a topographical map; and a transmitter connected to the control unit, wherein the control unit is configured to determine navigation information for use in assisting navigation of the ship based on the virtual representation, and the control unit is configured to cause the navigation information to be transmitted by the transmitter of the control centre to the ship; a receiver configured to receive the surroundings information, a control unit connected to the receiver and configured to determine a dynamic virtual representation of at least part of the environment based on the surroundings information, wherein the dynamic virtual representation comprises a topographical map; and a transmitter connected to the control unit, wherein the control unit is configured to determine navigation information for use in assisting navigation of the ship based on the virtual representation, and the control unit is configured to cause the navigation information to be transmitted by the transmitter of the control centre to the ship; wherein the navigation information comprises course heading information, wherein the control unit is configured to generate an instruction to sense the surroundings information representative of at least part of the environment, wherein the control unit is configured to cause the transmitter of the control centre to transmit the instruction, and wherein the beacon comprises a receiver configured to receive the instruction, wherein the beacon comprises one or more manoeuvring units for controlling movement of the beacon in water, and wherein the controller of the beacon is connected to the receiver of the beacon and is configured to control the one or more manoeuvring units based on the instruction.