What is the largest diocese in the Anglican Communion? There are two answers to this question.
The largest diocese in the Communion, in terms of land mass, is the Diocese of the Arctic in the Anglican Church of Canada. The diocese of the Arctic covers 1.5 million square miles of the northernmost region of North America.
The largest diocese in the Communion, in terms of area, is the Diocese of Polynesia, in the Anglican Church of Aotearoa, New Zealand and Polynesia. The Diocese of Polynesia includes an area of 11.5 million square miles in the South Pacific.