It is only a matter of time before a diver dies in the waters surrounding the Astrolabe Reef, Tauranga divers warn.

Photo: SUPPLIED / Darryl Torkler

The exclusion zone was reopened earlier this week for divers and fishermen in vessels under 500 tonnes, signalling five years of salvage work on the Rena Shipwreck coming to an end.

There has since been as many as 20 boats in the area at any given time, with people diving and fishing as the Rena wreck rests in waters as deep as 56m.

Tauranga Dive director Jared Ross said shipwrecks could also pose a real risk to divers.

Weather conditions for diving in the area were not ideal most days - and it was an accident waiting to happen.

"Someone is going to get lost inside that ship, so it'll take a life. That place is only good to dive maybe two days out of one month, because of the conditions.

"It's realistically a no brainer - somebody is either going to get hurt or someone is going to lose a life."

On Thursday night the Police Dive Squad held a meeting at a local fishing club, as part of a bigger campaign around dive safety.

Senior Sergeant Bruce Adams said the squad had been doing training exercises on the reef, and warned it had real risks which should be taken seriously.

"Even for us it's a challenge.

"Obviously we're planning in case things go wrong, and in this place with its isolation you're 11 miles offshore, very exposed to the weather and conditions which could change at a moment's notice.

Mount Maunganui Underwater Club captain Russ Hawkins, who has been going to the Astrolabe Reef since 1970, helped draft guidelines for diving and fishing around the reef.

Two diving sites near the bow of the ship have been marked with orange buoys and Mr Hawkins said as long as people stayed within those sites and only dived when the ocean conditions allowed they would be safe.

"We've been to many many meetings over the last couple of years about the wreck access plan. Providing they go by the plan and use those marked buoys and the physical structure of the wreck, there should be no problem at all."

Photo: MARITIME NEW ZEALAND

Diving in the wreck's stern section, marked with yellow buoys, was not recommended due to the depths at that location, except for qualified technical divers.

But Mr Ross said that was where people would want to go.

The clear water made it hard for divers to judge their depths - and easy for them to get carried away, he said.

"The visibility out at Astrolabe on a good day is very very good, going down and seeing the top of the ship, or especially on the stern section it could trap a few people ... it would be very easy to get a little bit confused on your depth, or just unaware of your depth."

There was international interest in diving the site, but he had told people to be cautious.

Senior Sergeant Bruce Adams echoed that message, and said that all possible safety measures should be taken before diving in the area, to ensure everybody gets home safely.

Photo: SUPPLIED / Sweeney Vesty

The volunteer Maketu Coastguard team had also received funding to have an onsite advisor at the reef for the initial period of its re-opening.

Maketu Coastguard president Shane Beech said there had been a lot of interest in the reef and another safety concern was the amount of traffic in the area with divers in the water.

"The dive trails themselves are very clearly marked for the divers, but again you known you have got fishermen out recreational as well and commercial fisherman, and obviously there's cray fishermen too within the area, so yeah it's a case of everybody sort of obeying by the maritime rules and all getting along together."

View safety updates on a website provided by the Astrolabe Community Trust, which was set up by the Rena's owner and insurer.