Thousands of volunteers are cleaning up hundreds of miles of coastline this weekend.
Litter on more than 400 beaches, from Plymouth to the Shetland Isles, will be collected and recorded as part of the annual Marine Conservation Society (MCS) Beachwatch event. The charity will use the information to target future campaigns.
There has been a 90% increase in the amount of rubbish on the coast over the past decade, with major sources being beach visitors, fishing debris, sanitary waste - particularly cotton bud sticks - and shipping waste, according to MCS.
The organisation says that, as well as being an eyesore, the litter is a "major threat to many vulnerable marine animals".
MCS Litter Projects Co-ordinator Bethan Jones said: "We're determined to make Beachwatch 2006 the biggest and most successful ever. MCS has been organising Beachwatch events since 1993 to turn the tide on litter at hundreds of beaches across Britain.
"Beachwatch provides the data MCS needs to tackle coastal litter at source, and to directly target the most common items found."
She added: "Taking part is easy, and volunteers will be helping to clean hundreds of kilometres of the UK's coastline as well as supporting our campaign to reduce litter on our beaches and at sea.
"This weekend is a real global snapshot of the state of marine litter."
More than 3,500 volunteers took part in last year's Beachwatch weekend, cleaning and surveying over 300 beaches and collecting nearly 3,000 bags of litter.
An average of 1,981 items of litter per kilometre surveyed was recorded in 2005 - equal to one piece of litter every 50 centimetres.
