People lined the seafront, especially at the Round Tower and Square Tower this afternoon.
HMS Queen Elizabeth started to sail out of the naval base at 3.45pm and then made her way slowly out of the harbour.
Here are pictures of the crowds from today.
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Read More... . Crowds in Old Portsmouth Crowds wave off HMS Queen Elizabeth. Picture: Finnbarr Webster/Getty Images Photo: Finnbarr Webster/Getty Images
5. HMS Queen Elizabeth Crowds wave HMS Queen Elizabeth. Picture: Finnbarr Webster/Getty Images Photo: Finnbarr Webster
6. HMS Queen Elizabeth Crowds wave as HMS Queen Elizabeth leaves Portsmouth. Picture: Finnbarr Webster/Getty Images Photo: Finnbarr Webster/Getty Images
7. HMS Queen Elizabeth People line the shore of the Hot Walls to watch HMS Queen Elizabeth leave Portsmouth. Picture: Andrew Matthews/PA Wire Photo: Andrew Matthews/PA Wire
8. HMS Queen Elizabeth The Royal Navy aircraft carrier HMS Queen Elizabeth passes the Round Tower as it leaves Portsmouth. Picture: Andrew Matthews/PA Wire Photo: Andrew Matthews/PA Wire