Thresher (SS-200) Her crew hears scraping noises along the bow as the USS Thresher gets hooked on a line and almost captured. Relieved when the "thing" didn't explode, the USS Thresher prepares to dive deeper to avoid depth charge attack. But the sub won't go down -- in fact, gauges show that she is rising in the water. Full speed ahead and quick maneuvering are needed to escape the giant hook.