# SUBSAFE

When a Cold War Test Drowned a Crew: The Thresher Disaster and the Limits of Submarine Safety

The sinking of the U.S. submarine Thresher on 10 April 1963 killed 129 sailors during deep‑dive trials and exposed fatal vulnerabilities in submarine design and emergency systems. The disaster prompted the SUBSAFE safety overhaul and remains a cautionary precedent for modern navies operating nuclear‑powered vessels in deep and poorly charted waters.