A display system for providing a 3-dimensional visual representation of an environment, the system comprising a display device and a processor, the processor being arranged to: receive information of the environment from at least one environment sensor; generate a representation of the environment using the received information from said at least one environment sensor; and output display signals representative of the received information to the display device, such that at least a portion of said generated representation of the environment is displayed in a display window of said display device, wherein the processor enables a user to selectively display said portion of the representation in said display window from one of a plurality of viewpoints from within said representation using a user interface, characterised in that said generated representation of the environment is displayed in a display window of said display device together with a display reference marker representing a location within said representation of the environment, the displayed portion being selectable by a user by re-positioning the display reference marker within the generated representation of the environment, each viewpoint comprising the display reference marker at a fixed location within said window and within said representation, the processor enabling the user to selectively position said display reference marker within said representation using said user interface, the processor being arranged such that the portion of said generated representation of the environment displayed in the display window follows the topography/bathymetry of the representation of the environment as the user navigates the display reference marker within the representation. receive information of the environment from at least one environment sensor; generate a representation of the environment using the received information from said at least one environment sensor; and output display signals representative of the received information to the display device, such that at least a portion of said generated representation of the environment is displayed in a display window of said display device, wherein the processor enables a user to selectively display said portion of the representation in said display window from one of a plurality of viewpoints from within said representation using a user interface, characterised in that said generated representation of the environment is displayed in a display window of said display device together with a display reference marker representing a location within said representation of the environment, the displayed portion being selectable by a user by re-positioning the display reference marker within the generated representation of the environment, each viewpoint comprising the display reference marker at a fixed location within said window and within said representation, the processor enabling the user to selectively position said display reference marker within said representation using said user interface, the processor being arranged such that the portion of said generated representation of the environment displayed in the display window follows the topography/bathymetry of the representation of the environment as the user navigates the display reference marker within the representation.