A Naval aircrewman with the Helicopter Sea Combat Squadron 25 died in the snorkeling incident Saturday in Piti.
The Navy identified him as Petty Officer 3rd Class Daniel Perez from California.
"Petty Officer 3rd Class Daniel Perez was found unresponsive in the water near Fish Eye in Guam Saturday where he was snorkeling with friends," Deputy Public Affairs Officer Christian P. Hodge of Joint Region Marianas Public Affairs confirmed in a statement.
"They performed CPR and contacted emergency services. An ambulance transported Perez to the U.S. Naval Hospital where he was declared deceased. He was 22 years old and from California."
Guam emergency responders were called to a total of three incidents of swimmers in distress Saturday in a span of four hours.
A 17-year-old girl and a 30-year-old man were rescued after they went over the reef in Asan.
Four tourists were rescued with the help of bystanders at First Beach in Ipan after they also were swept over the reef.