A group of five fishermen who were left clinging to a large rock after their boat sank were saved by pure chance when a rescue helicopter on a training mission spotted them some 15 hours later.

Large waves can be seen hitting the fishermen in the footage as they hold on to the rock with all their might while the rescue team begins its descent in a helicopter, before lowering a chair and lifting the men up to safety.

The fishermen were left stranded on the rock off a small island in the state of Selangor, Malaysia, on Thursday, 18th August, due to harsh weather conditions, for some 15 hours, according to local media.

Three of them had reportedly gone to the island to fish, with two others then being sent out to pick them up when they failed to return, but the boat sank, leaving all five stranded on the rock.

The fishermen were rescued the following morning at around 10.20am by the Malaysian Maritime Administration (APMM) after waving at a helicopter belonging to the Subang Maritime Air Station (SUMS) that happened to be carrying out routine flight training in the area.

The helicopter was carrying two pilots along with three crew members trained as rescue swimmers.

One of the fishermen, Mohd. Razwan stated: “We then immediately waved our hands for help because we were worried that the situation would become more serious.”

According to SUMS station chief and maritime captain Syed Islam Shahajam, the fishermen could have died due to their lack of safety jackets in the harsh weather conditions.

He added: “However, all the victims were saved when rescue swimmers managed to get them onto the helicopter using the ‘winching’ technique.”