Princess Mabel (left) and Princess Beatrix (right) of the Netherlands attend the Royal Netherlands Society of Engineers (KIVI) 2016 Prince Friso Engineering Award ceremony in Delft on March 16, 2016. The award is named for Dutch prince Johan Friso, who was the son of Princess Beatrix and husband of Princess Mabel. The prince was seriously injured in a skiing accident in 2012 and died in 2013.