Divers have encountered dark and dangerous conditions inside one of the holds of container ship Rena's sunken rear section.
They swam into the hold on Saturday after laboratory tests of water samples showed it was safe to enter the section that broke off the wreck two weeks ago.
The same calm sea conditions that saw the crane barge Smit Borneo remove 19 containers from the forward section of the wreck on Friday also allowed Svitzer Salvage to start the next phase of assessing how to deal with the submerged section.
Having completed an extensive inspection of the outside of the sunken hull, they needed to understand what was going on inside the holds in order to build up a complete picture.
Svitzer spokesman Mathew Watson said divers reported that the hold was full of debris with stuff floating around everywhere.
"It was a mess of smashed containers and cargo. It was not a terribly pretty picture.
"They are going into a dark and murky zone. It is very dangerous, even in calm conditions."
Mr Watson said the divers needed to do this work in order for Svitzer to make informed decisions on what could be done with the aft section and its contents, including the debris. After encountering dangerous conditions on Saturday, no attempt was made to enter other holds yesterday and Svitzer was looking at ways of getting better access to the holds.
Mr Watson said the focus remained on getting containers off the deck of the bow section of the Rena stuck on the reef.
Six more containers were removed on Saturday, but with the Smit Borneo having difficulty holding its position for long periods of time so close to the reef, no containers came off yesterday. It brought the total number of containers removed since the Rena broke in two to 39.
A helicopter continued to empty a second container of bags of milk powder while on-water shoreline clean-ups continued at Bowentown Heads at the northern end of Tauranga Harbour.
Plans were in place for two more containers to be retrieved from the Bowentown Heads area over the weekend.
Braemar Howells dispatched skips to collect debris washed up at East Cape.
Elsewhere in the Bay, a fast-response craft was operating close to shore while teams collected debris from beaches and coves in the vicinity of the Rena.
The MetService forecast for the coming week was for mostly fine weather.