The Underwater Demolition Badge is an obsolete badge of the United States Navy which was first created during the Second World War. The Underwater Demolition Badge was established as a decoration for members of Navy Underwater Demolition Teams (UDTs) and is considered a predecessor decoration to the modern day Special Warfare Badge.
The Underwater Demolition Badge was originally worn as a patch on the upper sleeve of a Navy uniform. The badge was awarded to the members of the U.S. Navy Underwater Demolition Teams and became a breast badge in the 1950s. As Underwater Demolition Teams began to be phased into the Navy SEALs, the Underwater Demolition Badge was used as a template for the new SEAL Badge.