Das Boot ending explained (spoilers)

[Kevingracy]

While crossing the Strait of Gibraltar, the U-Boat is attacked by British cruisers and begins to sink. They sink below 300 metres and just as it seems the boat is about to explode under the pressure, they hit a sand bar and teeter for awhile. With their main tanks capsized and unable to surface, the men start to move water by hand, the work made even more excruciating because of the lack of oxygen. Just as it seems the men are about to die, the Chief's plan works and the ballast tanks kick in, and the boat starts to rise. The U-Boat arrives at the port to a hero's welcome, only to be strafed by British bombers. Lt. Werner runs out after the bombing is complete to find most of the crew dead, among them Johann, 2WO, Ullmann and Preacher. Werner then sees the Kaleun propped up against the docks as he watches his boat sink. Just as the U-Boat slips under the waves, the Captain collapses and dies.