Organizers say Sunday's cooler weather is perfect for the athletes competing in the Michigan Titanium Triathlon at Versluis Park in Plainfield Charter Township.
The athletes began competing with a swim start at 7AM and it's possible the final athlete won't cross the finish line until around midnight.
The athletes had three different lengths to choose from: a full Ironman, half Ironman, and Olympic distance tri. This is the only opportunity in the state of Michigan to compete in an Ironman length race.
Organizers tell WZZM it takes 400 volunteers to pull of a race of this magnitude. Race co-director Ann Vidro says it also takes great coordination from the township as roads must be closed.
Vidro encourages the public to come out and cheer on these athletes. Versluis Park is located at 3650 Versluis NE Park, Grand Rapids, MI 49525