Laurel Silver-Valker slid off the edge of a scuba tour boat called Sundiver Express and into the ocean off Santa Catalina Island at 9:35 on the morning of Dec. 29, according to a police report.

She was looking for lobsters in the underwater cliffs and crannies below Ship Rock, a popular dive site a few miles northeast of the island’s Two Harbors.

The 45-year-old mother of two from Tustin was a regular on Sundiver trips, even volunteering as a crew member for the Long Beach-based tour company so she could spend as much time as possible in the ocean she loves.

At first, the dive seemed to be going well. A Facebook post from Sundiver at 10:06 a.m. shows two photos of Ship Rock and this caption: “Gorgeous day and a full boat!”

A short time later, according to police, the Sundiver Express left the Ship Rock area.

But Silver-Valker wasn’t on the boat.

“They went to a different dive site before realizing that she was not on board,” said Sgt. Dave Carver of the Los Angeles County Sheriff’s Department.

At some point, the Sundiver returned to Ship Rock, where crew members began a search.

Around noon, Carver said, the captain of the 43-foot boat called the Coast Guard to say Silver-Valker was missing.

Rescue teams have continued that search for more than two weeks. On Thursday, as many as 30 divers went back to Ship Rock but, again, found nothing.

Her fate remains unknown. Police say Silver-Valker is classified as a missing person; her family is planning a memorial.

“We just keep hoping she’s on a fishing boat somewhere with no radio, so they haven’t been able to reach us,” said one of Silver-Valker’s five sisters, Valerie Silver, of Los Angeles.

“But if she were to choose how she would have gone, and where, it definitely would have been in the ocean doing what she loved.

“So there’s some sweetness to that.”

IT’S HAPPENED BEFORE

This isn’t the first time Sundiver has left a passenger behind.

In 2010, a court awarded $1.68 million to a Santa Monica man who was abandoned by Sundiver. Daniel Carlock floated for five hours off the coast of Newport Beach until a boat full of Boy Scouts happened to spot him and scooped him from the sea.

Lobster diving is an inherently dangerous sport, and experts say it’s possible being left behind had nothing to do with Silver-Valker’s disappearance.

In the fall of 2014, the local dive community was rattled when five lobster divers died in unrelated accidents, six days into the start of the fishing season. None of those cases involved a boat leaving a diver.

Carter can’t yet say whether Silver-Valker had trouble while diving for lobsters or resurfaced to find the Sundiver Express had left her behind.

Kyaa Heller, who’s identified as captain of Sundiver International on the company’s website, declined to comment for this story.

The U.S. Coast Guard also is investigating how Silver-Valker disappeared.

Lt. Cmdr. Nathan Menefee said federal regulation requires all masters of passenger vessels to have an “active accountability of passengers aboard.” Sanctions could be issued against the credentials of a mariner found to be negligent or engaged in misconduct, he added.

Greg Elliott, who operates the Bottom Scratcher, a 63-foot charter boat based in San Pedro, said he has taken divers to Catalina for 29 years. He gives passengers a number, takes their name, conducts a roll call and physically checks that they are aboard before the leaving a dive location.

“You make sure you see everybody and that they answer the roll call,” Elliott, 74, said Thursday. “That’s the best system.”

‘DIVING WAS HER LIFE’

Silver-Valker took up diving as a hobby around 16 years ago.

Silver said her sister was a special education teacher at the time, with stints working for a couple of high schools and the Orange County Department of Education.

Several years ago, Silver-Valker suffered a back injury. Then she was diagnosed with fibromyalgia, a disorder that causes chronic pain. She had to rely on disability payments and part-time work as a private tutor to get by. She also volunteered with boat crews so she could continue pursuing her passion for diving without spending a lot of money.

Silver-Valker often dived for lobsters as a form of therapy, her sister said. Sometimes, Silver said, her sister would perform yoga stretches underwater, taking advantage of the buoyancy.

“Diving was her life.”

In online posts, dive friends call Silver-Valker a “mermaid” and “SpiderMan underwater.” They describe her as “joy made flesh” with a smile that was “contagious.”

That outlook is what drew fiancé Tom Gordon to her when they met in February 2013.

Soon they were taking Silver-Valker’s service dog, Maple, for walks on the beach. And, on holidays, Gordon would give her books about the world’s best dive spots.

“We figured we had another 30 years together,” Gordon said. “So we could hit one or two a year and be great.”