Emergency indicator (5) for signalling emergency situations comprising an electronic circuit (70) arranged to signal emergency situations through intermittent light signals and a light-weight shell (20) shaped so as to contain the electronic circuit (70) and to render the indicator (5) impermeable to water and apt to be self floating.

The present invention refers to a lens for a signal light, which lens is configured to convert a first distribution of light rays emitted from a light source (23) into a second distribution of light rays. The lens comprises at least three sectors and each lens sector has at least one internal surface (42i-44i) and at least one corresponding external surface (42e-44e) arranged to convert the first distribution into the second distribution. The internal (42i-44i) and external (42e-44e) surfaces form an overall internal surface (40i. 140i) and a corresponding external surface (40e, 140e) free from undercuts. At least one sector has an internal surface (43i) arranged to refract the light rays emitted from the light source (23), and at least two external surfaces (43e1, 43e2), wherein a first of the two external surfaces is arranged to reflect the rays refracted by the internal surface (43i) and a second of the two external surfaces (43e2) is arranged to refract the rays reflected by the first external surface (43e1). The invention also concerns a method of manufacturing the lens and a signal light, in particular for naval use.