The invention comprises an apparatus comprising a water-proof housing assembly comprising a housing (20) and a display panel (10, 32), and incorporating an enclosure (30) containing electrical apparatus, wherein said display panel is formed from a clear material (16) encapsulating a visual display (12) and/or a light-source (34) and said apparatus is capable of operating in water at a pressure of at least 300 bar without ingress of water into the enclosure. The apparatus may be used as an instrument or a lighting unit in sub-sea environments. The invention comprises further a light-source attachment for a powered apparatus comprising a light source embedded within a block of clear material (16) and means for mounting said block on the powered apparatus such that a connector connects the light source to a power source within the powered apparatus.