Clean Up Australia Day is the country's largest community clean-up, with more than a million volunteers claimed. Groups, schools and businesses register a site and receive a free kit; individuals join a listed clean-up. The Clean Up Cam app lets you log what you find.
Honest caveat: clean-ups remove what is already out there and make great local data, but they do not stop the flow. Use the day to count and photograph branded items and send the results to your council or the Australian Marine Debris Initiative (AMDI) database as well.
To give money instead: register.cleanup.org.au/become-a-changemaker (one-off or monthly; registered with the Australian Charities and Not-for-profits Commission (ACNC), donations above $2 tax-deductible).
How to start: register a site at cleanup.org.au/register-a-clean-up/ or join one at register.cleanup.org.au/join-a-clean-up