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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. Crowds in Old Portsmouth
Crowds wave off HMS Queen Elizabeth. Picture: Finnbarr Webster/Getty Images Photo: Finnbarr Webster/Getty Images
1. HMS Queen Elizabeth
Crowds wave as HMS Queen Elizabeth leaves Portsmouth. Picture: Finnbarr Webster/Getty Images Photo: Finnbarr Webster/Getty Images
2. HMS Queen Elizabeth
Crowds wave as HMS Queen Elizabeth leaves Portsmouth. Picture: Finnbarr Webster/Getty Images Photo: Finnbarr Webster/Getty Images
3. HMS Queen Elizabeth
Crowds wave as HMS Queen Elizabeth leaves. Picture: Finnbarr Webster/Getty Images Photo: Finnbarr Webster/Getty Images
4. HMS Queen Elizabeth
The Royal Navy aircraft carrier HMS Queen Elizabeth passes the Round Tower as it leaves Portsmouth Naval Base. Picture: Andrew Matthews/PA Wire Photo: Andrew Matthews