Has 200% speed when in a sub with fewer than 5 drillers (so it can't be used as helmsman).
At each outpost she contacts, a mark (in the form of a square bottom left) of the owner's color is placed.
Any sub (friendly or enemy) gain +0.5 speed increase between two square marks of the same color (outposts with squares of two different colors don't gain a speed increase).
Realistic reasoning: Oceanographers can find underwater currents to maximize sub speed. The squares represent their research stations.
This spec would be great when a smuggler isn't available, has a farther reaching effect, but has the risk factor of an enemy being able to use it.
Possible balance: speed effect only possible if other outpost is within sonar range.

Feedback?

I know I'm posting a lot of ideas, better to get them down when feeling creative than forget them later

This is a really cool idea, but I feel like it could be manipulated in some way by any allies-turned-enemies.

As a ocean dweller i know she runs on tides, maybe a good equalizer could be that u get a huge boost, say 400% when the tides running with you. Then 5 hours later u get a slack tide of no improvement about a hour long, followed by a negative effect of let just put it -100%. That way it makes it more forgiving on target over a longer distance.