FINNSIRIUS entered service on 15 September 2023 as the first of Finnlines' two Superstar vessels for freight and passengers. The ships were part of the company's EUR 500 million green investment programme, which also covered three freight vessels delivered from 2022 onwards. Her sister FINNCANOPUS joined the route in February 2024.

In May 2024, FINNSIRIUS received a Shippax Award. The award recognised a 24 per cent increase in cargo capacity to 5,200 lane metres, a doubling of passenger capacity from 554 to up to 1,100, and the ship's advanced energy-efficiency technology.

"FINNSIRIUS has done exactly what she was built to do: carry more passengers while reducing emissions per passenger and per cargo unit. She and FINNCANOPUS have been warmly received by leisure travellers and families as well as business groups, and today the two ships play a central role in our Sweden–Finland service," says Marco Palmu, Passenger Director at Finnlines.

Both vessels were designed with energy-saving technology, including battery banks, air lubrication and zero-emission shore power connections. Finnlines data shows that in 2024 the pair used 22 per cent less fuel per nautical mile on the Sweden–Finland route than their predecessors, FINNSWAN and EUROPALINK. By 2025, fuel efficiency had improved by a further 11 per cent compared with FINNSIRIUS' 2023 performance on the same route. The figures are based on verified operational data.

"Emissions performance is not only about technology. How a ship is operated matters at least as much, and our crews have played a major role in these results," adds Palmu.

On board, FINNSIRIUS combines freight capacity with restaurants and bars, a spa, a gym, conference facilities and family-friendly areas. A new passenger terminal opened at Långnäs in May 2026, and passengers travelling via Åland can now transfer there between FINNSIRIUS and FINNCANOPUS. This has made day cruises between Sweden and Finland easier. In September 2026, Finnlines also launched a new bus connection between Stockholm City Terminal and the port of Kapellskär.

© Shippax