Revellers have kept the new year celebrations in full swing at a series of events across Britain and Ireland.
Crowds amassed in the centre of London to see dancers, acrobats, cheerleaders and marching bands take part in the annual New Year's Day Parade.
The colourful event - the 32nd of its kind in the capital - featured about 8,000 performers from around the world and was watched by the many thousands of people who lined the streets.
Around the coasts and away from the main cities, thousands of hardy people braved chilly sea waters to take part in traditional New Year's Day dips.
In Scotland - famed for its Hogmanay celebrations the night before - 1,100 participants from 21 countries took part in the annual Loony Dook at South Queensferry, west of Edinburgh.
The sell-out event began with a parade along the town's High Street before the brave participants plunged into the waters in the shadow of the Forth Bridges.
Around half of those taking part in the spectacle wore fancy dress. Notable costumes included three people dressed as the Forth Bridge and another group in Wizard of Oz outfits.
At the other end of the country, fancy dress was also a popular choice for people swimming in the sea at Whitmore Bay in south Wales.
Now in its 34th year, the swim originally started when five members of a local lifeguard club decided to shake off their hangovers with a bracing dip.
In England, some of the locations chosen by swimmers included the waters of the Solent, Whitley Bay on the north east coast and Scarborough beach in Yorkshire.
Derbyshire also saw the return of the Mappleton Bridge Jump, an annual unofficial tradition where some people jump from Okeover bridge into the River Dove in Mappleton.
At Bray seafront in Co Wicklow, Ireland, Santa hats were a popular choice among the revellers taking part in the yearly charity swim.
The New Year's Day fun came just hours after thousands of revellers packed cities across the UK to see in 2018, with fireworks captivating crowds in London and Edinburgh.
Crowds took to the streets to join lively celebrations as the emergency services tackled one of their busiest nights of the year.
Scotland's ambulance crews received 2,565 calls between 7pm on New Year's Eve and 7am on January 1 - up by more than a third compared with the same time last year.
During the first hour of the new year, the London Ambulance Service (LAS) said it answered 337 calls with a number of patients treated for alcohol-related illnesses and injuries.
The fireworks display in London featured a soundtrack dominated by women to mark the centenary of women being granted the vote, while cities around the world staged similarly impressive spectacles.
More than 100,000 ticket-holders watched London's New Year's Eve fireworks, featuring songs by Aretha Franklin, Annie Lennox, Ariana Grande, Dua Lipa and Florence Welch among those included in the women-only second half of the world-famous show.
More than 10,000 fireworks lit up the capital's sky during that sold-out event, prompting huge cheers from the lively crowd.
Scotland Yard confirmed fewer Metropolitan Police officers were working during this year's celebration, but security at the event appeared tight, with armed police on patrol and security barriers erected.
In Edinburgh, tens of thousands saw in 2018 against the backdrop of Edinburgh Castle.
Around 75,000 people attended, with live music, DJs, street entertainment and the "ultimate fireworks display" from the landmark.
Copyright (c) Press Association Ltd. 2018, All Rights Reserved.