Salvors on board the stricken cargo ship Rena are getting close to the start of pumping operations to remove the remaining 358 tonnes of oil on board.

Maritime New Zealand Salvage Unit manager Kenny Crawford says a third 'hot tap' is being installed into the submerged number five starboard wing tank to raise the pressure enough to enable oil pumping operations to start.

Rena is grounded on Astrolabe Reef, the rocks are visible underneath at low tide. Photo: LOC

Hot tapping is a technique where seawater is pumped into the submerged tank to raise the level of oil to enable it to be pumped out.

Kenny says a third tap will increase the amount of seawater being pumped into the tank, and also raise the amount of pressure to push oil along 150 metres of hose into the tanker Awanuia moored off the stern of Rena.

'The pumps are in place and the hoses are connected. Divers are working in the hold next to the tank installing the hot tap this morning so pumping can begin.”

It is expected to take 100 hours to pump the 358 tonnes of oil remaining in the starboard tank.

The container barge ST60 was towed out of Tauranga port to begin sea trials this morning, to confirm its capability and stability.

Operations to transfer containers from the Rena to the ST60 will only begin once all the oil has been removed from the vessel.

A total of 35 transponders have been attached to containers to track their location if they were to fall into the ocean. A further 200 are on their way to Tauranga from the United States.

Braemar Howells, contracted to handle the salvage of containers, has two vessels conducting sonar sweeps of the sea floor to locate containers lost overboard during the storm three weeks ago.

MNZ National On Scene Commander Rob Service says teams of people are continuing shoreline cleanup work today including New Zealand Defence Force personnel working at Mount Maunganui, contractors at Harrison's Cut and volunteers at Papamoa.

Rock washing using sea water to flush out pools of oil has begun around Mount Maunganui.

One oiled little blue penguin was captured at Mount Maunganui overnight and is now being cared for at the Oiled Wildlife Facility.

Two teams are carrying out shoreline sweeps for further oiled wildlife on Motiti Island today, and other teams are working around the coast on the mainland and on Matakana Island.

Associate Transport Minister Nathan Guy was in Tauranga yesterday for a briefing on the salvage operation, the oil spill response and container recovery.

He visited the Oiled Wildlife Response Centre in Te Maunga and says it is 'fantastic” that pumping will soon begin from the number five starboard tank, but cautioned that Rena's condition continued to deteriorate.

'At any time the circumstances could change, and that could be from weather factors or the structural state of the Rena.”