"The students are looking forward to seeing the fruits of their work, and to seeing what their new Panamanian 'sister city' looks like on the video.
"Once the song is released, it will be uploaded to YouTube for the world to see."
Ms Wilkie says although Castro is not a well-known name in New Zealand, he is a Grammy winner and celebrated on the international stage.
With his nine-piece band El Tuira, named after a major river in Panama, he has produced four internationally acclaimed albums.
Ms Wilkie says Castro was very impressed with the "strength and pride" he saw among young Maori in New Zealand, and was moved by the poetic quality of Maori language and music, so was very eager to create a piece of work with the students he met.
"Whanganui High School music and Maori departments, led by Jeannette Jones, Brent Holt and Ash Patea, leapt at the chance, and a full-day collaboration resulted in audio files and video footage accompanying Romulo back to Panama."
The Whanganui footage of waiata, poi and haka has been woven together with music and recordings of Castro's band, Caribbean trio the Black Diamonds, a Panamanian primary school choir and scenes of Portobelo.
The song is performed in three languages - Spanish, English and te reo Maori - with the Maori lyrics written by Ash Patea.
"Ash's translations were a perfect complement to the sentiment of the song, expressing the sharing of stories across cultures and the importance of our rivers and seas," said Ms Wilkie.
The visit and collaboration was made possible with help from the Whanganui District Council and organised by the Whanganui Hispanic Culture Group, who also run the annual Latin American and Spanish Film Festival in the city.