On July 1, 2016, Australian took control of Norfolk Island. This official document, 3 pages, covers the requirements for yachts and small craft entering Norfolk Island waters. It includes where to find the reporting requirements and how to obtain a visa. This is now a mandatory requirement for all yachts planning to stop in Norfolk Island.
Also included are the contact details for Border Control on Norfolk Island.
Those that have to divert to Norfolk due to boat, or crew, or weather problems can of course stop if this is a matter of safety. This document, and the other Norfolk Island document in YIT cover this. It helps to have the information required for check in sent on ahead.