Smoke rises from sea in Helsinki as e-scooter battery burns underwater

An electric scooter battery caught fire underwater off Helsinki’s Eira beach on Sunday morning, producing thick smoke and a sulphur-like odour, Yle reports.

A journalist working for the broadcaster, Kaisa Erola, witnessed the incident. She described hearing a small popping sound before a sharp column of smoke rose from the sea. The smoke briefly thinned at times but quickly intensified again, accompanied by bubbling at the water’s surface.

Onlookers gathered at the scene, questioning whether it was safe to swim. Though Eira beach is not an official swimming spot, a nearby pier is a popular place for bathing.

Later in the afternoon, Erola returned to the area and saw a rescue diver at work. Authorities later retrieved the burning scooter, along with several others, from the water.

Kim Lassila, duty fire chief at Helsinki City Rescue Department, confirmed the fire involved a lithium battery from an electric scooter. He explained that such batteries can ignite even underwater due to their multi-cell structure. If one cell is damaged, it can overheat and trigger a chain reaction, causing the others to catch fire sequentially.

Lithium batteries can burn without oxygen and are difficult to extinguish, often requiring cooling to stop the reaction. They also emit toxic fumes, and contact with water can produce corrosive hydrofluoric acid.

Lassila assessed that the risk to swimmers at Eira beach was low due to the volume of water relative to the battery’s size but stressed that removing the scooter was the safest course.