The swim route in today's Ironman event in East Cork was cancelled due to the weather.
The event was due to be Ireland's first-ever full-length Ironman course.
Met Eireann issued a Status Yellow Rainfall warning earlier today for Waterford and Cork ahead of "thundery downpours".
2,300 participants are completing the full marathon and 180 kilometre cycle in the altered race.
Sergeant Adrian Lomasney from Midleton Garda Station said road closures are in place:
"The times for the road closures will vary according to when the cyclists get past them. The N25 will not be impacted.
"The cycle route will be going under the N25 at Midleton and will be going over the N25 at Youghal so we will encourage as many motorists to use the N25 and try and avoid the minor roads."
