Organisers of the George Bass Marathon have been forced to change the course for leg two of the race.
Torrential rain, large surf and poor visibility have made conditions too dangerous for the 19-kilometre leg from Moruya to Tuross.
Rowers will get underway at around 9am at Preddy's wharf on the Moruya River and race three laps of the river to finish at the town wharf.
Marathon organiser Andrew Edmunds said he regretted changing the course but safety of the competitors and support craft was paramount.
"Conditions just didn't allow for a race at sea today,” he said.
“Instead we have are using a contingency plan for a 15-kilometre row on the river which will test the rowers."
Mr Edmunds said competitors also had a tough night camping, with Moruya High School recording a high level of rain.
"We hope to finish early to allow rowers time to dry their camp sites and get ready for the rest of this challenging week."
The daily presentation planned for Tuross has been cancelled. It will take place this afternoon at Moruya Golf Club.