Two investigators from the Transport Accident Investigation Commission are due to board the Rena this morning to secure information from onboard recorders and to begin interviewing crew as part of the Commission's inquiry into the grounding which begun yesterday morning.

Rena, caught on the Astrolabe Reef.

The investigators are travelling to the stricken vessel aboard a Port of Tauranga pilot boat. They are expected to remain onboard the Rena today and possibly tomorrow.

The scope of the inquiry is still evolving along with the continuing event and as well as seeking to explain the grounding it could include, for instance, the final extent of any environmental damage and aspects of the post-accident response and salvage.

The Commission's safety focused inquiry will seek to explain how the grounding occurred and what, if anything, could be done to prevent a similar event happening again.

The inquiry could take a year to complete, but the Commission has the option to issue interim reports or urgent safety recommendations should the circumstances warrant it.

The final inquiry report will be provided to the International Maritime Organisation in fulfilment of New Zealand's international treaty obligations for maritime accident investigation.

The Commission is a standing Commission of Inquiry headed by three Commissioners which investigates selected maritime, aviation and rail events with the potential to produce new safety learnings.

It is has a staff of about 20, including 10 investigators, and is independent from any government, regulatory, or other investigation agency.