Lt. Col. John Hennessey loved his family, bird-watching, reading, trips to Costa Rica and scuba diving. Being in Iraq for a year made him appreciate it all that much more.

A week ago yesterday, the Army Reservist was at the beach near Dillingham Airfield with fellow Iraq War veteran Lt. Col. Todd Spillers, reflecting on all they had to be thankful for.

"He or I said, 'I could die right now and be happy, sitting on a beach, watching the North Shore waves roll in. Life is good,' " Spillers recalled yesterday.

Hennessey, 46, died four days later, on Sunday, while scuba diving off Portlock. A fellow diver found the Minnesota man's body near the Spitting Caves area.

About 135 Hawai'i and Mainland Army Reserve soldiers with the Fort Shafter-based 322nd Civil Affairs Brigade recently returned from Iraq. Most returned through Hawai'i.

At least two brigade soldiers were wounded in roadside bomb attacks. But to have a fellow soldier die back in Hawai'i is something none of the soldiers was prepared for.

"To go a whole year in Iraq and come back safe, and have this happen, it's just really horrible," said Lt. Col. Mary Carothers, who served with Hennessey and lives at Aliamanu Military Reservation. "I'm very sad, because he was just a wonderful person."

A memorial service is planned for 2 p.m. Saturday in the Schofield Barracks main chapel. Hennessey's wife, Dr. Barbara LeTourneau of St. Paul, Minn., is traveling here with her sister, son and Hennessey's sister.

Dive-tour operators brought Hennessey ashore after he was found about 9 a.m., and emergency workers were unable to revive him, officials said.

The Honolulu Medical Examiner's Office yesterday said determination of the cause of Hennessey's death awaits further studies. Toxicology results will be obtained and tissue samples will be examined, an official said.

LeTourneau, an emergency-room physician, told the St. Paul Pioneer Press that her husband didn't drown.

"The cause of death was apparently a natural event," she said.

Scuba diving was a favorite sport of her husband, and he had started diving in Costa Rica where they owned a home, she said.

Hennessey, who worked for a unit of General Motors Acceptance Corp. in Minnesota, was assigned to the 322nd for an unfilled spot.

The civil affairs brigade is heavy on senior leaders, and Hennessey was chief of operations for civil-military operations, and later chief of plans. He was based at Camp Victory, one of a handful of big U.S. military bases that ring Baghdad International Airport.

Fellow soldiers said Hennessey was a big man, weighing more than 200 pounds, and was trying to lose weight. But they said he ran and lifted weights twice a week and was in good condition.

Hennessey was a U.S. Military Academy graduate — something he was humble about, said fellow brigade member Lt. Col. Stacey Yamada.

A meticulous planner, Hennessey was known by friends as someone who liked to point out birds in Baghdad and knew music like few others. Once he got started talking about Costa Rica, he was hard to stop.

He also took full advantage of his time in Hawai'i.

"He loved Island life, so when he got the opportunity to come here and redeploy out of here, he just wanted to take advantage of everything that Hawai'i has to offer," Carothers said. "He had a smile on his face from the time he hit the ground."

Reach William Cole at wcole@honoluluadvertiser.com.