Members of Our Seas Our Future, along with consultants EY, ran a joint "no butts" clean-up, targeting cigarette butts and other rubbish, along Sumner beach on Saturday.
A group of almost 50 volunteers took part in the clean-up.
And they found more than just cigarette butts. A large volume of microplastics - very small pieces of plastic that occur in the environment as a consequence of plastic pollution - was also collected, said OSOF Christchurch event co-ordinator Ruby De Grut.
“Beach clean-ups open our eyes to the many ways our community interacts with our environment, having lasting adverse impacts," she said.
"It was so great to work (with) the lovely team from EY in Christchurch and other locals.
"The sun was shining, and everyone was both extremely interested and engaged in collecting the overwhelming amount of microplastics and butts we ended with.
"Each volunteer leaves the event with a greater understanding of how their daily choices interact with their local marine environment.
"The information they pass on to their friends, family and colleagues may seem small, but are in actual fact immeasurable."
“We had an incredible turn out and collected an alarming amount of microplastics, butts and other trash.
"Huge thanks to everyone who came down to join us and to EY and Our Seas Our Future for making it happen.”
For more information on Our Seas Our Future or to volunteer, visit the group's website or Facebook page.