Man dead, another missing after boat capsizes near Venus Bay

One man is dead and another is missing after a boat capsized near Venus Bay, off South Australia's west coast.

Police, Country Fire Service (CFS) and State Emergency Service (SES) volunteers are searching for the missing man, a 17-year-old from Victor Harbor, after the boat capsized in rough conditions early Friday morning.

It's believed they were about 400 metres offshore when the rope for their wakeboard wrapped itself around the boat's propeller.

A huge wave struck the boat, causing it to capsize.

Three men were onboard, one, a 22-year-old from Smoky Bay, managed to swim to shore.

Another, a 22-year-old from Wudinna was rescued from the water and taken to shore where he suffered a cardiac arrest.

He was rushed to the Streaky Bay hospital in a serious condition, but died when he arrived.

Winds of up to thirty knots and a five metre swell are hampering search efforts.

The Police rescue helicopter is assisting with the search.