Geographe Bay was the calmest the SunSmart Ironman WA has seen on Sunday for the international event.
More than 1,800 are participating in the event with people from 36 countries from across the world involved.
The 3.8km swim began at 5.30am with the professional males first in the water.
Australia's Luke Bell was second out of the water and onto the bike for the 180km ride.
The professional women were next in line and Australia's Lisa Marangon got a great lead in front of her competitors.
Another Australian Rebecca Hoschke was second to get out of the water and onto the bike.
Photos by Jemillah Bickerton, Tasha Campbell and Jade Jurewicz.