The event, which attracts visitors from around the globe, sees people dressed as Vikings march through the streets of Lerwick to recreate its ancient Viking past, in a tradition dating back to the 19th century.
Shetland and neighbouring Orkney were ruled by the Norse for about 500 years until they became part of Scotland in 1468.
The festival stems from the 1870s when a group of young local men wanted to put new ideas into Shetland’s Christmas celebrations.
9. The Jarl Squad set light to the galley in Lerwick on the Shetland Isles during the Up Helly Aa fire festival. Originating in the 1880s, the festival celebrates Shetland's Norse heritage.
The other criteria for participation are that guizers must be aged 16 or older and have lived in Shetland continuously for five years Photo by ANDY BUCHANAN/AFP via Getty Images) Photo: ANDY BUCHANAN
10. Participants take part in the Up Helly Aa festival parade through the streets of Lerwick
Participants take part in the Up Helly Aa festival parade through the streets of Lerwick, Shetland Islands on January 31, 2023. - Up Helly Aa celebrates the influence of the Scandinavian Vikings in the Shetland Islands and culminates with up to 1,000 'guizers' (men in costume) throwing flaming torches into their Viking longboat and setting it alight later in the evening. Photo by Andy Buchanan / AFP Photo: ANDY BUCHANAN
11. Participants take part in the Up Helly Aa festival parade through the streets of Lerwick
Up Helly Aa celebrates the influence of the Scandinavian Vikings in the Shetland Islands and culminates with up to 1,000 'guizers' (men in costume) throwing flaming torches into their Viking longboat and setting it alight later in the evening. Photo by Andy Buchanan / AFP Photo: ANDY BUCHANAN