The Marine Conservation Society holds its Beachwatch Big Weekend over 18 and 19 September.
And PADI Project AWARE runs its International Clean-up Day a week later, on 25 September.
Both ask for help from the public for seashore work but are grateful to any divers willing to clear debris from below the low-water mark.
Beachwatch is described by the MCS as “the biggest annual clean-up and litter survey in the UK”. Last year more than 4600 volunteers collected some 342,000 items from beaches around the country.
The organisation publishes the annual Beachwatch Report, which serves to support the MCS Campaign for Clean Seas and Beaches, aimed at “Government, retailers, industry, manufacturers and the general public”.
Information gathered can also contribute to updates of the organisation’s Good Beach Guide, where findings have a bearing on water quality.
To find out more about Beachwatch and associated activities, click here.
PADI Project AWARE’s International Clean-up Day is a global event, with some 15,000 volunteers from about 100 countries set to take part.
It is held in partnership with the Ocean Conservancy’s International Coastal Clean-up.
PADI Project AWARE has stated that some six million tonnes of rubbish enter the sea every year to wreak havoc on environments and creatures.
Volunteers can join organised clean-ups or set up their own. For general information about the event internationally, click here.
For information about clean-ups in the UK, call the PADI Project AWARE Foundation in Bristol on 0117 300 7313 and speak to Domino Albert or Caroline Davey.