Lt. j.g. Aaron Fowler, 29, became unresponsive while training with the Marine Corps at Marine Corps Base Hawaii in Kanehoe Bay and was later pronounced deceased at a hospital.
Fowler entered the service in 2012 and joined San Diego-based Explosive Ordnance Disposal Mobile Unit One in January.
"Our deepest sympathies go out to Aaron’s family and friends, and we join them in remembering and mourning this brave warrior," Rear Adm. Joseph Diguardo, Jr., commander of Navy Expeditionary Combat Command, said Wednesday.
"His decision to join this elite special operations community was a testament to the dedicated and selfless character he embodied and his legacy will endure in our ranks through those he inspired by his service."
The NCIS is currently investigating the incident.
Explosive Ordnance Disposal Mobile Unit One locates and clears explosive hazards in support of Navy and interagency operations.