Image: Juha Salo

Lohtaja resident Juha Salo found himself in the right place at the right time on Sunday, when a shoal of ice balls appeared in the beach at Ohtakari island, just north of Kokkola on Finland’s west coast.

Salo said he had witnessed another mass of ice balls in January 2018, however they were much larger at the time – up to one metre in diameter. This time they were much smaller.

"The biggest ones were maybe the size of a head. Many were the size of an orange, a ball or an egg," he noted.

Salo as well as Finnish Meteorological Institute (FMI) ice specialist Patrick Eriksson speculated that the balls form when pebbles moved around by the motion of the waves began to gather ice.

Another explanation would be that floating lumps of ice expanded and became round after moving along the sea floor. A third option would be a combination of both theories.

However the first option best explained the consistent size of the balls. Salo said that he opened up one of the ice balls to test the theories and found a bit of sand to which the ice had attached itself.

Seasonal surprises: Ice balls and ice stacks

In early November, another sighting of the peculiar marine phenomenon, this time in the shape of eggs, was recorded at Hailuoto island in Northern Ostrobothnia.

However underwater photographer Teemu Lakka from Vääksy in southern Finland said he had track the formation of ice eggs for many years.

The ice balls aren’t the only icy curiosities to fascinate Finns. In spring 2017 thousands of people flocked to the seaside to marvel at ice stacks that towered several metres high and which apparently formed in one night.

According to Eriksson such sightings are not unusual and are quite common in places such as the western bank of Hailuoto. Ice stacks have been seen north of Kokkola in locations such as Ohtakari, and Marinkainen as well as even further north in Himanka and Kalajoki.

They are much less common in the archipelago.