On Saturday, rescue officials received several calls to save people who had fallen through thin ice into freezing Gulf waters.
The most serious incident took place in Tammisaari, where a woman drowned after trying to save a dog near Heimosholmen Island.
One person went through the ice with a snowmobile in Virolahti. The person was pulled from the icy water and airlifted by helicopter to hospital in Helsinki.
Near the island of Tirmo in the Porvoo archipelago, the ice gave way under a person some 20 meters from the shore, near a ferryboat. The person managed to struggle to the shore, but rescue services were also alerted to the scene.
Presently only inlets are properly frozen. According to the Border Guard, the ice is still weak in places, where it usually is strong.
The beautiful, though chilly weather has brought outdoors enthusiasts onto the ice, for walks, skating and snowmobile rides.
Skater sinks near Lauttasaari
On Sunday a middle-aged long-distance skater fell through the ice about 150 metres from Helsinki's Lauttasaari island. The man, aged around 50, was able to climb out by himself.
Passersby heard his shouts and called rescue services. They brought him ashore using a raft and took him to hospital.