Can somebody explain the subsplosion?

So I've noticed in a number of game recordings that players at various points just launch huge numbers of one-driller subs from one or more of their outposts, aimed at almost every other outpost on the map. Is this like a death cry thing (subterfuge equivalent of 'gg')? A masking-your-movements thing? Something else entirely?
Either way it looks pretty cool I have to say
Either way it looks pretty cool I have to say
