Based on the search results, there are two aircraft carriers that are mentioned in San Diego: the USS Midway and the USS Nimitz. However, the USS Nimitz is not currently in San Diego as it returned from deployment on June 28, 2023. On the other hand, the USS Midway is a historical naval aircraft carrier museum located in downtown San Diego, California at Navy Pier. It is currently a museum ship and is open to the public for tours and activities. Therefore, the aircraft carrier that is currently in San Diego is the USS Midway.