Easy - one giving if correct AND DETAILED!
please give me at least 2.

Well you see theres this guy named MrBeast thats taking little kids money and is having one of his slaves eat a water bottle for every dollar

Well recently Team Seas has come out for every dollar donated I think it's 1 pound of trash so by donating would be one.

The second would be volunteering to help clean up for example a beach.

For more lasting impact would be to have a machine that collects the trash at where the rivers and streams meet the ocean this will lead to less trash in the ocean. There is a great example of this machine by Mark Rober gives a detailed explanation.