The International Young Naturalists' Tournament (IYNT) is the international counterpart to the SYNT. In contrast to the SYNT, students from all over the world participate. The participants are aged 12 through 16. The age limit is set such that participants of the IYNT must not turn the age of 17 years during the calendar year of the respective IYNT competition.

The format is similar to the SYNT: Three teams (each consisting of 6 students) compete against each other in so called Science Fights. They take turns presenting and defending their solution to a given problem, criticizing the solution of the opposing team and reviewing the performance of the two preceding teams. The performance of all three teams is assessed by a jury. The teams have to try to convince both their opponents as well as the jury of the quality of their scientific work and results and of the understanding of physics.
The whole tournament is accompanied by an extensive social program and usually lasts eight days.

More information about the IYNT and the organization behind the IYNT can be found on their website.