Giovanna Tomanik Diamante (born June 26, 1997 in São Paulo) is a Brazilian swimmer. At the 2014 Summer Youth Olympics in Nanjing, she won a silver medal in the Mixed 4 × 100m freestyle relay. She also finished 4th in the Mixed 4 × 100 metre medley relay; 5th in the Girls' 4 × 100 metre freestyle relay; 8th in the Girls' 50 metre butterfly; 10th in the Girls' 100 metre butterfly; 15th in the Girls' 200 metre butterfly; and 20th in the Girls' 200 metre freestyle. She has qualified to represent Brazil at the 2020 Summer Olympics.