It's 100 years since the Titanic set sail from Southampton on its famous journey to New York.
More than 1,500 of the ship's crew and passengers died when it hit an iceberg and sank, five days into its trip across the Atlantic.
It was the biggest, fastest and most luxurious passenger ship of the time.
Many of the cruise liner's staff were from the city of Southampton, where a special ceremony took place.
More than 650 descendants of the crew members and 600 local schoolchildren took part at the dock where the boat set sail.
A minute's silence was held to remember those who died, and people threw wreaths into the water.
The schoolchildren paraded through the streets, each holding pictures of the ship's crew.
The parade finished at the new SeaCity Museum, which was formally opened by Olympic rowing champion James Cracknell.
Cruise follows Titanic's original route
As well as the ceremony, a memorial cruise has also set sail to mark the anniversary.
The Titanic memorial cruise set off on Sunday and is taking some of the family members of those who sailed on the original boat on a special journey to New York.
The MS Balmoral will follow the same route as the Titanic, even visiting the spot where the liner sank.
Check out Blue Peter, this Thursday, for a special programme from the Titanic Belfast museum - 5.45pm CBBC Channel.