What was the major strength and major weakness of the U-boat?

The major strength of the U-boat, or submarine, during World War I and II was its ability to conduct stealthy attacks against enemy shipping, allowing it to sink merchant vessels without warning and disrupt supply lines. However, its major weakness lay in its vulnerability when surfaced, as it had limited defensive capabilities and could be easily targeted by aircraft and surface ships, particularly during the later stages of the war when anti-submarine warfare tactics improved significantly.