Pacific waters hold secrets of World War II

Last month, HMNZS MANAWANUI hosted dive teams from multiple nations to locate remnants of war in Tuvalu.

When it comes to Operation Render Safe, the mapping and disposal of Unexploded Remnants of War (ERW) in the Pacific, the Royal New Zealand Navy has often relied on other countries’ vessels. This time, we provided the ride.
The Australian Defence Force-led mission combined the Royal New Zealand Navy, the United States Marine Corps and the Royal Canadian Navy in a week-long survey of Nanumea and Funafuti lagoons at the request of the Government of Tuvalu.

The mission, based off Hydrographic and Dive Ship HMNZS MANAWANUI, was to complete a reconnaissance of reported ERW and build a plan for a future disposal operation.

Arriving in Fiji, MANAWANUI picked up HMNZS MATATAUA clearance diving and military hydrographic detachment, their Royal Australian Navy, Royal Canadian Navy and Marine Corps counterparts.

The sites in Funafufi Lagoon provided no unexploded ordnance across a five-day search. The release of the area frees up the Government of Tuvalu to proceed with decisions on reclamation operations.

In contrast, just two days in Nanumea lagoon saw the discovery of 22 500-pound aerial bombs of United States manufacture and four small arms dumps of .50 calibre ammunition placed in ‘dump lines’ in depths of 10 to 18 metres. The approved search area only covered seven per cent of the lagoon, meaning there is still a long way to go to make the lagoon safe.

The RNZN military hydrographic side contributed by using a side scan sonar system and magnetometer to help locate objects of interest, which the dive teams could explore in further detail.

The teams completed 77 dive serials, accumulating 47 hours of dive time. In addition to diving into roughly mapped suspected ordnance, the teams conducted magnetometer coverage over an area of 2.62 square kilometres. They located 3,190 kg of ordnance in 24 sites, with the majority found at a depth of 15 meters. Based on the findings, the Australian Defence Force will send the Government of Tuvalu a full reconnaissance report and recommendations for future removal and disposal.

Lieutenant Commander Teina Hullena, Executive Officer of MANAWANUI – and also a clearance diver by trade – says the mission showcases the many ways the New Zealand Defence Force and partners provide value to the Pacific and help to stabilise environments and promote regional security. “This operation was the first opportunity for MANAWANUI to operate with an embarked international force over a sustained period. It’s a validation of the ship’s detached diving operations and a real capture of lessons learned.”