A heroic maritime rescue operation off the coast of Durban saved a Filipino seafarer in critical condition.

A 41-year-old Filipino seafarer is recovering in hospital after being rescued from a bulk carrier off the Durban coast during a complex maritime medical evacuation coordinated by the National Sea Rescue Institute (NSRI).

The operation unfolded on Wednesday after the crew member developed a serious medical condition while aboard the 229-metre vessel en route to the Port of Durban.

NSRI Durban station commander Etienne van Zyl said the organisation was first alerted on Tuesday morning after shipping agents requested an emergency evacuation.

"On Tuesday, 23 June, at 08h40, NSRI Durban duty crew were alerted by shipping agents requesting a medical evacuation of a 41-year-old Filipino male seafarer suffering from an emergency medical condition on board a 229-metre bulk carrier motor vessel approaching Durban from deep sea," Van Zyl said.