"Basically you could go into oil with that but it's not very nice," Mr Crawford said.
Divers were yesterday assessing the submerged hull section from the outside. They had reached as far as 44m at the back end of the ship. Their maximum depth was 50m.
A boat with a decompression chamber on its back deck was at the ship yesterday, tied to the tiny section of the stern's accommodation block that remained just above the surface.
Mr Crawford said said an initial assessment showed the stern section was pretty well stuck on the reef. There were no concerns at this stage that it would sink to the sea floor.
Gesturing to the mangled wreck from aboard the Tauranga Coastguard yesterday, Mr Crawford said: "It's not teetering there, it's not flexing up and down. That's about 12,300 tonnes of steel there. There is absolutely no concern that it is going to slide off."
Meanwhile, tug boats have dragged two empty containers off the bow of the Rena as salvors find new ways to remove cargo from the increasingly hard-to-access wreck.
The new approach to removing containers from the forward section of the Rena sitting on top of the reef was tried yesterday after the Smit Borneo could not get close enough to the port side of the wreck. The two empty containers were pulled off by tug and then lifted on to the recovery barge.
Ten containers were taken off by crane on Wednesday, which was the first day that conditions permitted the removal of containers since the Rena broke apart on January 8.
Up to 12 tonnes of bagged milk powder have been lifted off and transferred to a waiting barge.
Oil continues to leak from the Rena, with the weather helping to prevent the slick from coming ashore.
Maritime New Zealand national on-scene commander Mick Courtnell said less wildlife was being oiled and any birds were going directly to Massey University.
Twenty-eight birds were being treated at Massey of which 13 were expected to be released back into the Bay by the end of next week.
Only one of the significant numbers of dead birds found on Wednesday and yesterday morning had been oiled. Most were recovered from the Opotiki area, with 50 sent to Massey for post-mortems to check whether they had died from natural causes. Death from natural causes was common at this time of the year for juvenile penguins.
Mr Courtnell said the pockets of oil left in the wings of the duct keel were now expected to measure in the tens of tonnes.
The Braemar Howells recovery team continued working on several fronts yesterday, with the biggest focus on Waihi Beach and Bowentown Heads.
Spokesman Grant Dyson said plywood and MDF sheets had washed ashore at Waihi Beach, mostly around the surf club.
Fifty bags filled with latex gloves were washed up on beach at Bowentown and divers were planning to attach a line to a container at Bowentown's Anzac Bay so it could be winched ashore.
Five badly damaged containers retrieved from the sea or beaches were unloaded from a barge on Wednesday night, bringing to 64 the number of containers recovered since the Rena broke up.
Three containers have been located by sonar on the seabed between the Rena and Motiti Island, with debris continuing to be collected from the shorelines of White Island and Whale Island in the Eastern Bay of Plenty.