Calligaris started her Olympic career very early, obtaining her first national success at the age of 13. Despite having a short figure, she had excellent technique and very strong determination.
At 14, she set her first European record and led Italy to the Olympic podium for the first time at 1972 Summer Olympics, bringing home a silver medal for 400 m freestyle and two bronze medals, for 800 m freestyle and 400 m individual medley.
In the European Championships in 1974, she won two medals, one silver and one bronze. These were the last international achievements of her career, which ended shortly afterward.
She won a total of 76 Italian titles and broke 21 European records. Until Federica Pellegrini's second place in 200 m freestyle at Athens 2004, she was the only Italian woman to obtain an Olympic medal in swimming.