Thousands to cheer on yachts at start of Sydney to Hobart race

Thousands of people are expected to line the Sydney Harbour foreshore to send off the 70th Sydney to Hobart yacht race.

What started as an unheralded race in 1945 for nine yachts has grown into an event watched by millions.

It's one of three major races in the world and has become an iconic part of the Australian summer.

A 15-knot southerly breeze is forecast for the start of the race, but it's tipped to reach 20-30 knots by Friday afternoon.

Yachts will set off in three batches because of the large numbers taking part in the race.

Those wanting to catch a glimpse of the start of the race, but wanting to avoid the crowds, can venture to Rushcutters Bay, Watsons Bay, Cremone Point, Bradley's Head or just past Manly.

The race is expected to end on New Year's Eve in Hobart.