The balloon race, organised by South Green Infant and Nursery School in Billericay, Essex, resulted in a cash prize for a Finnish couple who were holidaying in the Viiratsi vald area of Estonia and found the well-travelled balloon.
There was also a cash prize for four-year-old Scarlett Grey, a pupil at the school, who had sold the ballon to her grandmother Jane.
Of the 1,000 balloons set soaring at the event, 60 were found by people in Hungary, Belgium and Germany, as well as closer to home in Kent, who replied by sending a letter to the school.
Headteacher Stephanie Ireland said that the farthest they had expected the balloons might reach would be France. They were surprised when they received a letter all the way from the Baltic country. She said that some letters even came with pictures and maps.
Ms Ireland said, 'The children get really excited when we announce at assembly that the school has received another letter. It's been a good learning experience for them and unexpectedly covered lots of areas of the curriculum, such as geography.'
The balloon race raised £2,600. It was the first of a number of events to raise money for the modernisation of the 40-year-old council-run nursery attached to the school.
The school needs around £200,000 to refurbish the 52-place nursery. Ms Ireland approached the council for funding but has failed to secure any money other than capital grant funding.
She said that they hope to gain £80,000 from fundraisers alone, at which point she plans to approach the council again for help.