Something like a rescue sub which would function like a reverse pirate.

It could break away from one of your own inflight movements, or join up with one.

Like an escape pod? Perhaps it could rescue a set percentage of the units on the sub?

One of the strengths of the game is the predictability of it as you set up movements possibly a day in advance.

Right now, the Navigator is the only specialist that breaks the predictability aspect of planning and I'm not sure if I would like to introduce another one.

Would you want this sub to be exactly like a pirate, where you target your own friendly sub and upon intercept it returns the combined sub to the nearest outpost?

Or were you thinking that this specialist travels on a sub and at any time you could essentially split the sub in two?

I've considered this very thing for quite a while, typically with martyr subs. Perhaps a sub that splits in the middle, 1 heading back to the Outpost that sent it and the other heading onward toward it's original target. However, with the Navigator already able to change directions, this would introduce a lot of bugs.

Another crazy idea a couple of us discussed is the idea of a Tugboat type sub. This sub can attach to an Outpost and can physically pull the outpost in one direction or another, toward another outpost, perhaps at 0.5x speed. The idea is to move an outpost closer to you and/or further away from someone else. Could be very beneficial for mines or other interesting strategies.

Again, would probably introduce a lot of bugs especially if another sub is en route to that outpost.

But I agree with Braxo, adding more to the problem of predictability is not good for a game like this.