Blackouts

Every so often a blackout occurs in the deep dark. The light will slowly flash on and off for 5 - 10 seconds, and then will completely go out for 10 seconds to 1 minute. The effect would be purely visual (nothing to do with light levels), and perhaps there is some kind of skulk effect or audio distortion as well. This would tie in with the whole "navigatign by sound" theme, and will make the deep dark even more spooky an dangerous.