Books are better for what it’s like to be in someone’s head. It’s been years since I read it, but I remember that Iron Coffins, by Herbert A. Werner gave some really good descriptions. One of my favorites was when the sub got stuck in the mud at the bottom and they all had to run back and forth from one end of the boat to the other, jumping up and down to try to rock it free, knowing that if that didn’t work they’d suffocate to death down there. I also read a couple from the U.S. perspective (Pacific theater) that were pretty good too, but don’t recall the titles.
Some reviewer’s descriptions on Amazon:
“It is hard to imagine how the crew lived like they did in their constantly rocking boat: without bathing for months, eating moldy food, suffering from constant humidity, freezing or roasting as the season might be (no airconditioning or heaters), and not having proper sanitary conditions (using a bucket in rough seas, etc.) Very good detail on u-boat life both aboard ship and in port.”
“When you come away with an idea of how it felt, right down to how it even smelled inside the U-Boat on patrol, the author has done a great job.”