The Princess Royal has unveiled the Lee Valley White Water Centre in Hertfordshire.
The facility is the first brand new venue for the London 2012 Olympic Games to be completed.
The £31m project, which incorporates the 2012 Olympic slalom canoe course, was finished on schedule and will be open to the public from April 2011.
Britain's top canoeists have exclusive use of the facilities until that time.
The venue, near Waltham Cross, will be operated by the Lee Valley Regional Park Authority and will offer the public rafting and canoeing facilities, on both the main 300m Olympic course and a separate 160m intermediate run.
The Princess Royal was joined by officials from Waltham Abbey Town Council at the ceremony.
The Princess Royal started a race between canoeists from the GB Olympic team
Silver medallist Campbell Walsh, who was one of the athletes to test the course today, said: “It's hugely exciting to test the rapids at the new Lee Valley White Water Centre for the first time.
The Olympic Delivery Authority chairman John Armitt said it was a “milestone” to complete the venue under budget and so soon before the Games.
What are these?