There's been a fire aboard submarine HMAS Waller off the West Australian coast.
The fire broke out on Thursday afternoon as the vessel sailed on the surface.
"Emergency response actions were taken to extinguish the fire. There were no casualties," Defence said in a statement.
However, as a precaution four members of the ship's crew involved in responding to the fire were landed for observation.
HMAS Waller had recently completed scheduled maintenance and was at sea as part of her return to operations.
A full investigation will be held.
