If you're looking for a fun event for the whole family then perhaps the cardboard boat race will do the trick. Hosted in Oxford, London on the Trend Avon River, this competition has families building boats out of cardboard.
The strange thing about the cardboard boat race is that the people look forward to the sinking of the ships. Of course, this is bound to happen since the boats are made out of cardboard and will sink the moment they get wet. Even though these boats will eventually sink, adults and kids still paddle a great distance before the boat goes down.