They are continuing to consolidate smaller parcels of engine oil from different compartments to pump them off the Rena.
No further buckling of the ship has been detected, but the ship continues to be closely monitored.
The container barge Sea Tow 60 (ST60), which holds two large cranes, has conducted sea trials including laying anchors to test the mooring systems that will be used when the barge begins removing containers from Rena.
The trials were held well away from the ship so as not to interfere with the oil removal, Mr Crawford said.
Vessels conducting sonar sweeps of the seabed in areas where the water is 30m deep or less are searching for containers that were lost overboard in a storm three weeks ago. Divers are checking items detected by the scans.
Wreckage of three containers has been removed from the Hicks Bay and Waihau area. Another two containers are yet to be removed from Motiti Island.
National On Scene Commander Rob Service said five teams of New Zealand Defence Force staff were working between Mt Maunganui and the Maketu Spit yesterday, assessing the state of the beaches, while another contingent was continuing with rock flushing oil removal trials at Mt Maunganui. A report of a large amount of oil at Waihi Beach had proved to be an algal bloom, Mr Service said.
"At this time of year when there are warm temperatures and calm seas, algal blooms are quite common.
"We expect to receive more reports of 'oil' that turn out to be algae, but we will always check them out to make sure."
Teams from the oiled wildlife response have continued to patrol beaches on the mainland and on Matakana Island, checking for oiled wildlife and responding to reports from the public.
About 50 people are working at the oiled wildlife facility, taking care of the 400 birds that have been cleaned, and the three still being treated.
Some of the birds were little blue penguins, which are being hand-fed twice a day as well as weighed and checked regularly.