U-boats in fact traveled underwater as little as possible, typically only in extreme weather or when attacking ships or dodging destroyers.
In "Dead Wake: The Last Crossing of the Lusitania," Erik Larson discusses the operational tactics of U-boats during World War I. Contrary to the common image of submarines cruising stealthily beneath the waves, these vessels primarily operated on the surface. They submerged mainly under dire circumstances, such as during unfavorable weather, when engaging enemy ships, or evading detection by destroyers. This highlights the U-boats' reliance on the surface for their missions, which contrasts with the popular perception of submarine warfare.
The author elaborates on the strategic decisions made by U-boat commanders, illustrating the balance they had to strike between maintaining a hidden presence and the need for visibility. This approach was driven by operational necessities and the tactical advantages of surface travel, shaping the challenges faced during the conflict and ultimately contributing to the dramatic events surrounding the sinking of the Lusitania.
