The Royal New Zealand Navy’s newest and largest ship, the HMNZS Aotearoa, has been practising its manoeuvres in the Marlborough Sounds.

The 26,000-tonne auxiliary ship, measuring almost the length of two rugby fields, has been doing training exercises and practising navigation ahead of overseas deployment later this year.

The ship had been circumnavigating the North Island when it made the surprise visit to the Sounds via Tory Channel on Wednesday, to practice in what one naval officer commander described as “one of the best pilot training grounds in the world”.

The ship’s captain, commander David Barr said the HMNZS Aotearoa and her crew had been extremely busy in the three years she had been on active service.

She provided disaster relief in Tonga following last year’s volcanic eruptions, and resupplied New Zealand’s Antarctic McMurdo research station with 10 million litres of fuel.

Barr said the on-board reverse osmosis system was one of the world’s most advanced desalination systems.

It enabled the crew to supply those affected by the Tongan eruptions with around 500 million litres of clean water, he said.

The fact that they were able to turn contaminated, ash-covered seawater into clean, fresh drinking water for the thousands in need was testament to the crew and the ship’s capabilities, he said.

HMNZS Aotearoa also delivered fuel and essential aid to the affected islands during their deployment to the Pacific.

Barr said the ship and her crew were equally at home in the Antarctic as they were in the tropics. The HMNZS Aotearoa was a purpose-built polar-class sustainment vessel well-equipped to tackle the cold and ice of the Southern Ocean.

HMNZS Aotearoa was to leave the Marlborough Sounds on Thursday before making her way back to her home port of New Plymouth, where the crew would take part in Anzac Day commemorations before enjoying a few days of rest and recuperation on shore leave.