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I was reading this https://earth.esa.int/documents/973910/1006684/RR3.pdf (Satellite Gravimetry) earlier today after seeing this article as I remembered nuclear submarines used gravimeters.

Is there any information on them being used to track other subs, as I was wondering if that was possible, I know they're apparently used to map the sea floor though.

Edit:

This is interesting:

"He showed a figure of gravity increasing by about 2 microgal over a 4-h period as men shoveled snow from the roof of the SG station" -

http://ethesis.helsinki.fi/julkaisut/mat/fysik/vk/virtanen/s...

The mass of a bucket of water, and an equally full bucket with a sub in it, is equal. Otherwise the sub would sink like an anchor or float like a boat.

True. The gravity gradients from the sub may be different, though.

Do you have any evidence a submarine conducting normal operations has been detected with a gravimeter?