Here are snapshots of them taken from interviews of family and friends:
SHINGO ALEXANDER DOUGLASS, California
Yeoman 3rd Class Shingo Alexander Douglass followed in his father's footsteps in joining a maritime branch of the military, enlisting in the Navy in 2014.
He started working aboard the destroyer that same year and last October joined his shipmates on a visit to an orphanage in South Korea as part of a community service project. Douglass was seen pushing a disabled orphan in a wheelchair, according to the San Diego Union Tribune.
His father, Ret. Marine Corps Master Sgt. Stephen Douglass, told the newspaper his 25-year-old son was an avid videogame player "and a really good kid."
He had just gotten promoted in May. A 2010 Fallbrook High School graduate in Fallbrook, north of San Diego, he was unmarried.
His family described him as "adventurous" and said his hobbies included scuba diving and tennis.
"Shingo served his Nation proudly, and we are also very proud of him and his service," his family wrote in a statement.
NOE HERNANDEZ, Texas
Gunner's Mate 2nd Class Noe Hernandez was a tremendous source of pride for his family, a relative told Dallas television station KTVT.
"We all came from poverty in Guatemala. He was the one who made it," said cousin Aly Hernandez-Singer. "We lived through his experiences. His travels."
The 26-year-old Hernandez, of Weslaco, Texas, had been stationed in Illinois, Italy, California and Japan since joining the Navy in 2009.
He died in the collision from a head injury as he slept, Hernandez-Singer told the TV station.
She said Hernandez met his wife in high school and also is survived by a 2-year-old son.
NGOC T TRUONG HUYNH, Connecticut
Sonar Technician 3rd Class Ngoc T. Truong Huynh, 25, always "had the brightest smile," his sister said.
He was selfless, Lan Huynh told WVIT-TV, of Hartford, Connecticut, and the family is coping as best it can.
Huynh graduated from Watertown High School and attended Naugatuck Valley Community College before enlisting in the Navy in 2014. The family moved to Oklahoma soon after.
Connecticut's governor has ordered flags to fly at half-staff in Huynh's honor.
XAVIER ALEC MARTIN, Maryland
Personnel Specialist 1st Class Xavier Alec Martin was trying to call his father after the vessels collided but didn't get through, his father told WJZ-TV in Baltimore.
All Darrold Martin can think of are his son's final moments.
The 24-year-old sailor, of Halethorpe, Maryland, followed in his father's footsteps and was quickly rising in the ranks, said Darrold Martin, who referred to his son as his best friend.
"It's very hard," the elder Martin said. "He's my only child, he's all I have."
Martin graduated in 2010 from Landsdowne High School, where he ran track and had many friends, said Daneace Jeffrey, Martin's aunt.
He loved being in the military and was considering turning it into a career.
"He always put others before his own safety," she said. "I'm sure in his last moments he was probably more concerned with the other servicemen than himself, that's the kind of person he was."
GARY LEO REHM JR., Ohio
Fire Controlman 1st Class Gary Leo Rehm Jr., 37, was three months shy of retiring when he was killed, his cousin tells The Chronicle-Telegram in Elyria, Ohio.
Friends and relatives described the sailor from Elyria as generous and easygoing. They say the Navy told his mother he died trying to rescue fellow sailors trapped in flooding compartments.
"When we heard that he ran in and helped save other sailors from drowning, we said that was Gary. That was Gary to a T," said Rehm's friend Christopher Garguilo. "He never thought about himself."
Rehm was inspired to join the Navy by his grandfather, a World War II sailor who took Rehm on tours of military planes and ships when he was a youngster. Rehm enlisted in 1998, right after graduating from Oberlin High School, said his aunt.
"He loved what he did," said Rehm's aunt, Virginia Rehm. "He was a very kind-hearted, happy person who worked hard. It's a big loss, it really is."
Gary Rehm is survived by his wife, his parents and a sister.
KYLE RIGSBY, Virginia
Nineteen-year-old Gunner's Mate Seaman Dakota Kyle Rigsby was a volunteer firefighter in his Virginia hometown before he joined the Navy.
The Palmyra resident and Fluvanna County High School graduate was a teenager when he signed up with the Lake Monticello Volunteer Fire Department in 2014, following in his mother's footsteps, news outlets reported.
Rigsby would "give his shirt off of his back for you," said volunteer firefighter Farrah Brody.
Assistant Fire Chief Jean Campbell described Rigsby as a dependable firefighter and called his death "a tragic loss."
Chase Karaca said he met Rigsby in fourth grade and they bonded over playing Pokemon.
The game sparked an interest for Rigsby in Japanese culture, so "it was a dream come true for him" to get to visit and "to be doing something for his country," Karaca said.
Rigsby enlisted in February 2016. He reported to duty aboard the Fitzgerald in November.
CARLOS VICTOR GANZON SIBAYAN, California
Fire Controlman 2nd Class Carlos Victor Ganzon Sibayan felt that serving in the Navy was "his calling" and he joined in 2013 after graduating from high school, a friend said.
Sibayan, of Chula Vista, south of San Diego, always made people laugh, Chase Cornils, a fellow cadet in Chaparral High School's Naval Junior Reserve Officer Training Corps, told the San Diego Union Tribune.
"He always had a cheerful attitude and a smile on his face," Cornils said.
An enlisted surface warfare specialist, the 23-year-old started working on board the USS Fitzgerald in July 2014.
This story has been corrected to show that Shingo Alexander Douglass first reported for duty on the USS Fitzgerald in 2014, not 2015.Copyright 2018 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.