Rick Jones wrote:

I seem to recall that one of the reasons it was/is popular for
submarines to hide under the Arctic ice was it was very noisy. Given
the cracks and tidal forces on Europa couldn't it be pretty noise too?


It could be, but I would think it would be less so than in the arctic
due to lacking anything like summer thawing and winter freezing. A lot
of noise in the polar oceans is probably due to icebergs toppling over
or fracturing and ice flows grinding together.
Still, ice fracturing can make a very weird and loud noise*. We hear a
lot of that come early spring on our local reservoir as the ice starts
to melt, and I didn't think of that problem in regards to under-ice
noise on Europa.

* Which is hard to describe - it sort of resembles the sound made by a
saw used as a musical instrument by bending it back and forth rapidly.
What it really resembles is the sound made when that guy punches one of
The Dirty Dozen in the top of his steel helmet in the latrine fight
scene in the movie "The Dirty Dozen". :-)

Pat