Trieste II (DSV-1) was the successor to Trieste—the United States Navy's first bathyscaphe purchased from its Swiss designers. The original Trieste design was heavily modified by the Naval Electronics Laboratory in San Diego, California and built at the Mare Island Naval Shipyard. Trieste II incorporated the original Terni, Italian-built sphere used in Trieste, after it was made redundant by the new high-pressure sphere cast by the German Krupp Steelworks. The Trieste sphere was suspended from an entirely new float, more seaworthy and streamlined than the original but operating on identical principles. Completed in early 1964, Trieste II was placed on board USNS Francis X. McGraw (T-AK241) and shipped, via the Panama Canal, to Boston.