The USS Dolphin (AGSS-555),a diesel-electric, deep-diving, research and development submarine.
She holds the record for deepest dive by a submarine, with over 3,000 ft. / 1,000 meters.
As part of the Maritime Museum of San Diego, she can be toured aft to bow, but there is very little room for photography inside and visitors must ascend and descend using ladders.

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