HMAS Anzac trained with two Indonesian Navy ships this month during Exercise New Horizon, a key biennial maritime high-end warfare engagement.

The exercise was conducted in the waters off Surabaya, Indonesia, as the final international activity of Indo-Pacific Endeavour (IPE21).

Anzac's navigating officer Lieutenant Dean Ryan said New Horizon was a great opportunity to train with Indonesia.

"It allowed the bridge and operations room teams to practise various warfare and navigational exercises, all of which greatly improved our interoperability with our nearest partner nation," Lieutenant Ryan said.

"This exercise has been one of the highlights of 2021 for me professionally."

New Horizon focused on building anti-surface warfare skills and increasing interoperability between the two navies.

Anzac joined the Indonesian Navy Ships KRI Gusti Ngurah Rai and KRI Malahayati in officer-of-the-watch manoeuvres, helicopter operations, tactical manoeuvring and anti-surface warfare serials.

A highlight was the surface gunnery practice, where the three ships formed a surface action group and simultaneously engaged a target with their main guns.

In boarding serials, the ships were unable to undertake actual boarding because of COVID-19 restrictions, however, each unit was able to observe the other and benefited from the practice.

"It was such a great opportunity to work with the Indonesian Navy, and their small boat driving skills were impressive," Leading Seaman Smith said.

The exercise ended with a sail-past at close quarters and an exchange of ceremonial piping before Anzac commenced her journey through the Lombok Strait on her way home.

Commander IPE21 Commodore Mal Wise said the activity was a fitting end to the IPE deployment, which included several virtual engagements between Australian and Indonesian officials.

"New Horizon provided Anzac ship's company an opportunity to build practical naval cooperation with one of Australia's most trusted security partners, and helped solidify our commitment to work together in promoting peace and stability in our region," Commodore Wise said.