sonar

"It's an unspoken rule, but it's what we are adhering to for the first time: there will be no active acoustic program on board the ship, no sonar" while in Russian waters, he explained.

This included mapping the seabed with sonar arrays and dredging up sediment samples, said the authority.

The steady ping of the enemy’s sonar waves bouncing off the boat’s metal hull made it all too obvious.

At the back of the aircraft are stored 129 active and passive sonar buoys which can detect underwater sounds.

In November 2023, Canberra accused Beijing's navy of using sonar pulses in international waters off Japan, which resulted in injuries to Australian divers.