Lapland Police are looking for a woman aged around 50 who went missing in the remote village of Saija in the Salla municipality.
On Monday, the police received a report of a passenger car in the water with no one inside it.
According to the lead investigator, police have not ruled out the possibility that the woman remains in the water. Another possibility is that she got out of the water and left the scene on foot.
Police believe the car was driven by a German woman with dark-brown, medium-length hair.
Saija is a small village located some 40km north of the centre of Salla, near the border with Savukoski. Salla and Savukoski are among Finland's most sparsely populated municipalities.
Police have been searching the area together with rescue and border guard officials. The search will continue on Wednesday, and police have appealed to the public for any information about the missing person.
Any possible sightings of the missing person should be reported via email to vihjeet.lappi@poliisi.fi, by phone at 0295 466 259 or WhatsApp at 050 415 5803.