Fog and drifting snow on Lake Lämmijärv on Friday blurred the EU's external border, leading to lost Russian and Estonian fishermen wandering over the de facto line into their respective neighboring countries.
In the morning, a solo fisherman from the Estonian side called authorities saying he had become disoriented and that his snowmobile had run out of fuel.
Local fishermen helped pinpoint his whereabouts - four kilometers on the wrong side of the border.
Border guards at Mehikoorma notified their Russian colleagues, who tracked him down and handed him over to the Estonian side where he was transported back to land.
Later that evening, a radar operator on the Estonian island of Piirissaar saw that a snowmobile had crossed the border from the Russian Federation. Border guards dispatched to the area found tracks passing repeatedly back and forth over the border.
The border guards apprehended three Russian citizens in a snowmobile pulling two sleds.
They, too, lacked navigational equipment - they did have a compass but said they did know how to use it - and said they had become lost. Like the Estonian fisherman, they were sent back to their home country.
Head of the Mehikoorma border guard station Arbo Sillaots said people often inadvertently crossed the border in such conditions, breaking the law. He reminded the public to carry navigational equipment and check the weather forecast before setting out.