The group of about 26 students were taking part in ''Ki Uta Ki Tai: From the Mountains to the Sea'' volunteer programme, which started on Friday and finishes today.
Yesterday, the students helped the Hawkesbury Lagoon Society plant 56 kowhai and 36 rimu trees.
Hawkesbury Lagoon committee chairwoman Shirley McKewen said it was great having the students to lend a hand.
''It's [difficult] getting lots of volunteers to come and do planting in small towns like this and so to get 26 people out working for a day, we just get a huge amount of work done,'' she said.
The students were also taught about the history of the lagoon and its wildlife.
Other activities during the week involved the group in learning about Maori culture, including a visit to Puketeraki marae, helping with planting on Huriawa Peninsula, at Karitane, and participating in a survey of Waikouaiti estuary.
