One November 24, 1968 the USS Dolphin dove to a depth of over 3,000 feet to become the world’s deepest diving submarine. Today the record still stands. The last of her kind, a diesel-electric submarine, was decommissioned in 2007 where she was configured to conduct deep water acoustic research, oceanic surveying, sensor trials, and engineering evaluations. She now resides at the San Diego Maritime Museum.
Official photo (stolen from the web)
Parked next to the Berkeley at the San Diego Maritime Museum.