The choices are endless.
If surfaced during the early years I'll drop to 30 - 50 m about every hour of game time, run silent, and have a good listen. At night, or away from the main routes, I'll leave it a lot longer, maybe 3 hours, unless I suspect something may be nearby.
I'm sure there are others out there who remain at the hydrophone most of the time underwater, but that's not for me
