Board Thread:Questions and Answers/@comment-24472316-20131214205655/@comment-4383275-20140214055437

Lightning has the attributes of fire and light, so its opposite would be water and dark.

Hmm...

A hydrothermal vent.

In case you don't know what those are, they're super-hot streams of water that shoot upward from the abyss beneath the barthypelagic (deep-sea, with anglerfish and all that) zone.