| Term: | Skylight |
| Definition: | From the point of view of the submariner, thin places in the ice canopy, usually less than 3 ft (1 m) thick and appearing from below as relatively light, translucent patches in dark surroundings. The undersurface of a skylight is normally flat. Skylights are called large if big enough for a submarine to attempt to surface through them, or small if not. |