Shipping lanes coming into the Port of Tauranga have been given the all clear at this stage by the New Zealand Defence Force, who are currently monitoring the lanes for sunken debris.

The C-Max Side Scan Sonar being put into the water. Photos by Tracy Hardy.

The NZDF is using sonar technology to detect and locate containers and debris which have fallen off the Rena.

The NZDF's primary objective is to ensure the shipping lanes are free of debris so that incoming and outgoing ships can travel to the Port.

Senior Media Advisor from Defence Communications Group Major John Gordon says there was no debris in the channel.

'Eighty eight containers have fallen off the Rena and are believed to have sunk within the Rena Exclusion Zone.

'The Navy is supporting Maritime NZ by maintaining port access for salvage operations therefore their focus is centred on the shipping channel and not the wider Exclusion Zone. By maintaining clear port access for the salvors, it has a secondary benefit of ensuring the Port remains open to commercial traffic.”

He says the team is out on the water daily and ensures that 100 per cent of the channel is checked for any new debris.

'This will continue for as long as Maritime NZ determines there is a risk of debris floating into the channel.”

The sonar – a C-Max Side Scan Sonar – transmits form both sides and is dragged behind the ship at about five to seven metres, depending on weather.

LHST Kieron Boardman looks at the data being fed back from the Cmax side scan sonar.

Hydrographic Survey technician LHST Kieron Boardman says they 'have scanned the entrance today and it is all clear”.

Port of Tauranga chief executive Mark Cairns released an update earlier today saying the general view is that most of the sunken containers have washed up on beaches and Motiti Island.

He says shipping movements and cargo operations will continue as normal (20 vessels over the next 24 hours), as well as the three cruise ships expected this coming week.

LHST Kieron Boardman shows what a container looks like when it comes up on the screen. This is one they detected earlier this week.