The Rena wreck has been cleared for use as a dive site, should the owners and insurer's application to leave the remainder of it on Astrolabe Reef be approved by the Environment Court.

Contained in resource consent information now available online at www.renaresourceconsent.org.nz is a report from Tauranga commercial diver, wreck explorer and underwater photographer Shane Wasik, who after considering the risks concludes diving Rena will be safer than other New Zealand wreck dives.

People will be able to dive to the Rena if the decision is made to leave it where it is.

'The hazards of diving the wreck by recreational divers, acting within safe diving practice guidelines and within the limits of their level of experience, are not considered to be significant when compared with other wrecks already in New Zealand,” says Shane.

That's if all the suggested mitigation measures are undertaken, along with wreck access management procedures, education materials and monitoring – as detailed in the consent application's Wreck Access Plan and Monitoring Plan.

'As with any other wreck, the Rena will never be completely ‘safe' to dive,” says Shane.

'However, the proposed measures will make sure that divers of average experience can explore the wreck in relative safety and the site is left in a responsible manner with more mitigation than other accidental wreck sites in New Zealand currently provide.”

There are risks, as with all recreational diving, says Shane.

With the accidental nature of the Rena and challenging environmental conditions at Astrolabe Reef, there are potential risks to divers. The Reef was considered an ‘advanced' dive prior to the Rena struck the reef on October 5, 2011.

'As such, the expectation is that divers should already be adequately prepared to dive there – regardless of the wreck,” says Shane.

'The Rena hasn't been artificially prepared and scuttled as a diving attraction, so will have potential risks common to other accidental wreck sites that recreational divers visit in New Zealand.”

Before the Rena collided with it, Astrolabe Reef was a notable recreational diving site both in the Bay of Plenty and New Zealand.

The reef has a unique topography with gullies, plunging walls, shelves, caverns and caves and is exposed to prevailing west or south westerly winds and oceanic swells.

Before October 2011, the reef was considered to be an ‘advanced' dive site.

Since the ship struck the reef an exclusion zone has prevented any recreational diving at the site.

The exclusion zone will be lifted and public access restored, as part of the consent proposal.

The wreck only occupies a small part of the total reef, so those wishing to explore it and not undertake a wreck dive will still be able to do so once the exclusion zone is lifted, says Shane.

The Rena site is the biggest, has the greatest depth range and gives the easiest access to depths exceeding recreational limits of all other New Zealand wreck dives.

The wreck site, including debris field, is estimated to be over an area of about 10,000m2 and ranges from about one metre at the bow section to 56m in depth at the lowest point of the aft section.

As part of the proposal, a Wreck Access Plan is to be provided which includes measures such as vessel manoeuvring arrangements and moorings, safe diving areas, safe boating guides and recommended operating conditions.

Implementation of this plan is considered to minimise many of the potential dive safety hazards to recreational divers on the wreck of the Rena, particularly immediately after the exclusion zone is lifted and interest in diving the wreck is likely to be at its highest.

The wreck and debris field occupy less than two per cent of the entire area of Astrolabe Reef. Even if the area above the normal 30m maximum recreational diving depth of the reef is considered, the wreck still occupies a very small proportion of the reef.

Normal diving exploration of the reef will continue much as it had before the Rena grounded, says Shane.

'However, it is noted that a result of leaving the wreck on the Reef will be that divers will want to explore the wreck.”

Following the grounding and break-up of the ship, work was done to reduce the bow section to one metre below low tide.

What remains of the bow is now in several sections. The proposal is to leave these sections on the reef.

Debris field:

The proposal is to leave the structural hull parts, equipment, containers and cargo in the debris field surrounding the wreck, following further clearance to remove where practicable:

• TCCA canisters, aluminium ingots, inorganic material, entanglement and other hazards to a depth of LAT -30m.

Aft Section, including any remaining cargo:

Parts of the hull structure of the aft section have broken off and part of the accommodation block has been removed.

The proposal is to leave what remains of the aft section including structural material, equipment and cargo still within it, the engine room and accommodation block to the level of D Deck.