The annual underwater clean-up is bring organised by Dive Otago as part of the international Project Aware Dive Against Debris programme, involving volunteer divers in 180 countries.
Dive Otago diving instructor and Project Aware co-ordinator Emma Young said local divers had been involved in the official clean-ups for the past two years, removing thousands of pieces of debris from Otago Harbour. The Professional Association of Dive Instructors (PADI) is also involved in the project.
The number and type of items are recorded as part of the ongoing international Project Aware survey of ocean debris across the planet.
''It is important that the debris is logged so we have a record of the amount of debris we have in our water and tidal areas,'' Ms Young said.
''We also do a clean-up of undaria [pest kelp] from the water at the same time as collecting the debris,'' she said.
''A lot of what we find are things like plastic bottle tops, cigarette filters, caps and lids from cans, bricks and chunks of cement,'' Ms Young said.
''We have [also] found more unusual items, such as shopping trolleys, chairs, and even a whole car bumper.''
Ms Young believed the majority of the items found were not necessarily dumped in the harbour but were either discarded on the ground and blown into the water or had come from refuse bins. Because of the tides and prevailing winds, a large amount of debris accumulated at Pilot's Beach or around the area of the ''molars'' sculpture.
''Of course, this material is dangerous to fish, sea mammals and seabirds, which is why it needs to be removed.''
Dunedin had a proactive diving community, which had been cleaning up the waters around the city for years, she said.
The Dive Otago- Project Aware Dive Against Debris underwater clean-up will also involve a beach clean-up at Pilots Beach. The public are invited to take part and help to clean up the area during the event, which will be held from 10am on Saturday, November 29.
Divers are asked to meet at 8.30am at Dive Otago, and non-divers are asked to meet at 10am at the Albatross Centre car park.
To sign up, phone Dive Otago on 466-4370, or find the event on Facebook.
