Tiny tiny grasshopper. Due to plentiful rainfall the whole area was either underwater or boggy, including the tracks, so exact location uncertain. I have seen one of these earlier in the year quite near here, but was surprised to see it hopping about at this time of year. Perhaps it was trying to get above the water.
Difficult to identify to species without a specimen that needs to be sent to the expert in Czeckia, although there is a very complex key by Rehn. They swim well especially the slender Paratettix that lives at water margins feeding on algae.