The crew on the Irish Navy vessel LE Eithne have rescued 367 migrants from a wooden barge in the Mediterranean.
The crew located the men, women and children in choppy waters about about 31 miles ( 50km) north-west of Tripoli in Libya, and all of them were safely taken off.
This morning's rescue operation took nearly three hours.
A Navy spokesman said the 278 men, 80 women and nine children were undergoing medical screening on the LE Eithne and being given food and water.
The vessel and crew were dispatched by the Irish Government in mid-May to assist Italian authorities in the humanitarian search and rescue operations in the Mediterranean.
Lieutenant Commander Eric Tymon told RTE’s News at One that the passengers were suffering from the effects of sea sickness and exposure to the sun.
“You could see the relief on seeing these Irish sailors arrive to take them off this unsafe raft to a safer place.”
“We can only imagine what conditions they’re actually fleeing from. You must put yourself in their minds to ask what would make them step into the vessel, which is unsafe, to be cast adrift in the ocean.”
Lt Cdr described sea conditions as "choppy" for Mediterranean standards, and he said it was “particularly tricky” transferring the passengers from one boat to another.
In a separate rescue operation, the naval vessel recovered an additional 100 migrants on a rubber craft, 70 kilometres north-west of Tripoli.
The operation commenced at 12.57 pm during a south easterly 1 metre high swell and finished at around 2.30 pm.
There are now approximately 460 migrants on board the LÉ EITHNE, receiving food, water and medical attention where required.
The Irish Naval Service is currently awaiting instruction from the Italian authorities for their next tasking. The LÉ Eithne will remain in the Mediterranean until mid July.