...or so it seemed. I spent a few hours stalking it and discovered...
4 Clemson class destroyers.
That was it.
How often are task forces this small? Or perhaps some other sub took down the main ships... I dunno. It ticked me off. They were somewhat far apart...
Approximate positions:
As noted, one DD was apparently searching for someone else. I only heard the DD's even when searching manually(25m deep, top-mounted hydrophones).
Once again, the magical Uboot => Brest teleporter saves the day!
Unrelated note: dolphins can move pretty fast...