The 44-year-old man suffered an apparent cardiac arrest and was rescued from the water by event lifeguards, said Eric Garvey, spokesman for the Jekyll Island Authority.
EMTs from the Jekyll Island Fire Department met the lifeguards on the beach and began performing CPR immediately, Garvey said.
The Georgia State Patrol said the EMTs responded at 8:15 a.m.
The man was transported to Southeast Georgia Health System’s Brunswick hospital where he was pronounced dead, Garvey said.
Garvey noted that four to six other swimmers were assisted, which he said is normal for a swim in open water, and none were emergency situations.
The state patrol, which will be the reporting agency in the death, said it did not yet have the man’s identity and was uncertain of whether his next of kin was aware of his death.
The Turtle Crawl offers competitors a choice of Sprint or longer Olympic distances. Competitors in the Sprint competition swim a quarter mile and those in the Olympic competition swim about 1.5 miles. In addition to a bicycle ride, there are also 5 and 10 kilometer runs.
The other events were completed without incident, Garvey said.
The Jekyll Island Turtle Crawl Triathlon is in its 10th year and typically draws about 700 competitors in May.