Participants retrieved 117 kilogrammes of plastic waste from the Katase Higashihama beach near Tokyo, which will host the sailing competition next summer.
In the summer of 2020, the Katase Higashihama Beach, near Tokyo, will transform into an Olympic sailing venue.
But on Wednesday, another kind of competition was being held.
Some 160 participants divided into 37 teams took part in a "trash collection challenge" to pick up waste to clean up the beach and mark World Environment Day.
A total of 117 kilogrammes of plastic waste was retrieved during the event which was hosted by Tokyo 2020 Olympic organisers.
Kosaku Ota, one of the organisers of the challenge, said that "we are really grateful to the Tokyo 2020 organising committee for holding this event and the people who gathered to help clean up the beach."
"I don't live far away from here and I did not realise the amount of debris and micro-plastics present on this shore. This is a great chance to open our eyes and care more for the environment".
Hiroko Abe, who participated, said that "days like these are a great lesson for kids, reminding us how important is to preserve the environment, and at the same time spend time at the beach".
The United Nations Information Centre in Tokyo also took part to highlight its 2030 Sustainable Development Goals programme.
Kaoru Nemoto, director of the UN information centre, flagged that Tokyo 2020 is "very committed to the issue of sustainability and also sustainable development goals, which are a set of common goals for the entire world leading to 2030, so that we can pass on this Earth, this planet, to future generations."
"In that sense, the issue of Marine plastic pollution is one of the biggest problem issues affecting the ecosystem," he added.