Container removal from Rena is on hold as long slow sea swells of up to three metres batter the ship causing dangerous conditions for salvors.

While the weather is fine and calm in Tauranga out at Astrolabe Reef, where Rena is grounded, large swells and tide conditions are lashing the vessel.

The rear profile of Rena that was once stacked high with containers. See Maritime New Zealand video footage of the shipwreck shot this morning below.

So far a total of 166 containers have been lifted from the ship stricken about 25km from Mount Maunganui since October 5.

There were 1368 containers originally, with 88 falling into the sea on the night of October 12 during a storm, leaving a total of 1114 containers still aboard.

Maritime New Zealand salvage unit manager Kenny Crawford says the operation is weather dependent and safety of salvors is always the priority.

The weather is being continuously monitored and Kenny says the salvage team is undertaking preparatory work while the swell prevents container removal.

'Containers that can be readily accessed are being taken off, and we can't put a time scale on the operation as we have good days and then days when none can be removed.

'Every container is unique and removal of deck containers needs to be carried out to allow access to the holds.”

'Health and safety conditions for the salvors are being constantly monitored, including gas detection.”

Twenty containers were lifted from the Rena on Tuesday and one container was removed yesterday, before northeasterly winds and rough seas halted operations.

Salvors remained onboard the Rena on Wednesday, working on the installation of rigging to prepare containers for removal.

A dive operation has been assessing the reef around the Rena in anticipation for moving the Sea Tow 60 once it has removed all containers within reach of its current position.

Almost all of the containers on the stern deck of the ship have been removed.

Shoreline surveys and clean-ups are continuing in Matakana, Maketu and Mount Maunganui.