Update, 12pm: Jeremy Brooke-Smith is the first competitor to arrive at Rottnest Island after winning the 23rd Rottnest Channel Swim in choppy conditions this morning.
Brooke-Smith reached the finish line in 4h 34m 36s and described the 19.7km race as a "hard day at the office". He was followed by Tim Hewitt in second place and Iain Melhuish in third for the solo men's race.
Jess Walker has taken back to back wins in the women's competition, reaching Rottnest Island in 4h 48m.
A record was broken for the mixed pairs as 24-year-olds Heidi Gan and Simon Huitenga finished the race in 4h 8m 11s.
The fastest team was Rottnest Express - comprising Paul Laver, Deane Pieters, David Locke and Liam Ryan - in 3h 55m 09s.
Team Euphoria, including swimmers Gene Williams, Patrick Hoey, Bobby Jovanovich and Josh Cicanese, was the first team to cross the line.
The fastest team was Rottnest Express in 3h 55m 09s.
The solo 220 solo swimmers set off from Cottesloe Beach this morning in rough conditions. It was a crisp 13C at the start line as the swimmers lined up but the water temperature was an inviting 26C.
South-south easterly winds of 10-15 knots were recorded at Cottesloe Beach at 6am.
Seas were 1-1.5m and the swell was less 0.5m-1m.
Solo swimmers Heather Bolton and Claire Morrison were among the first group of fifty to swim out this morning.
The two women, both aged 39-years, plan to swim alongside each other for the entire 19.7km race.
The pair said they had swam the channel as a duo and in a team but this year was their first solo swim.
“It was my stupid idea,” Ms Bolton joked.
“Its something we wanted to do before we turned 40.
“We’ve been training pretty hard and racked up about 680km of swimming in the past year.”
Ms Bolton said they expected to reach Rottnest Island in seven to eight hours.
Hundreds of spectators lined the beach this morning to support loved ones competing in the race.
Among them were Helenmary and Bryan Skyes who had come down to see their daughter Katrina set off.
Mrs Skyes, who was with her grandson Oliver, 9, said she was extremely proud of her daughter.
“It’s the second time she has done the solo swim so she went in this morning positive and confident,” she said.
“We’re all heading across to see her swim in Rottnest as well—very excited for that.”
Oliver, who attends North Cottesloe Primary School, said he would like follow in his mum’s footsteps and take part in the swim when he is older.
The youngest competitor in the race this year was Victoria Holman who turned 14-years last week, making her eligible for the race.
The oldest swimmer is Deiter Loeliger who turned 80 years old yesterday.
He is competing in his 15th solo swim and believes this year will be his last.
Premier Colin Barnett was on hand with the starters horn this morning to set off the nine waves of swimmers.
As each wave entered the water, brightly coloured swim caps bobbed up and down in the swell before quickly disappearing out of sight.
The swimmers are alone in the starting channel for about 500m before they are joined by paddlers. Only after the 1km mark, support boats are permitted to pull up alongside their swimmer.
The Westpac Lifesaver Rescue Helicopter hovered above the first stretch of the race. There was an unconfirmed sighting of shark 2km into the Rottnest Channel Swim at about 7.40am.
The species of the shark was unknown and it was reportedly spotted 500m west of the sailing boat Leeuwin, which was due to meet swimmers at the 1500m mark in the swim.
The area was searched by the Westpac Life Saver helicopter but nothing was found.
The last teams left Cottesloe Beach about 7.45am.