Charge laid a year after Tevita Kava died after falling overboard on a The Red Boats charter in Auckland's Waitematā Harbour

A charter boat company has been charged over the death of a man who fell overboard during a 30th birthday cruise a year ago.

And the Herald on Sunday can also reveal for the first time the man, 29-year-old Tevita Kava, has a 10-year-old daughter.

The Māngere man fell overboard during the Waitematā Harbour excursion on a Red Boats charter on June 3 last year.

His body was found in water near Te Atatū nine days later.

This week, Maritime New Zealand filed a charge against The Red Boats Limited under the Health and Safety at Work Act.

The company is charged will "failing to comply with duty that exposes individuals to risk of death or serious injury or serious illness".

Kava's cousin, Ngaire Speedy, said the family were still deeply grieving Kava.

Family had initially kept the fact he had a daughter quiet, to protect her.

But they now wanted people to know the little girl was among those affected by the tragedy.

"She's doing all right. She lives in [Kava's native] Tonga and she's finally accepted it but I think we won't tell her about the court [charge] ... until the end."

Kava was standing at the back of the charter boat during an evening cruise when he fell backwards into the water.

At the time, friends on board said Kava fell when a ramp gave way.

Red Boats owner Andrew Somers said at the time the ramp wasn't broken and staff had later tested it.

He didn't know how the ramp, usually locked and tied in place, became unlocked and untied, Somers said last June.

The matter is before the coroner, and an inquest will take place at a later date.

Somers said this week he did not yet know enough about the charge to comment.

The company will make its first appearance on June 20 in the Waitākere District Court.

Speedy said family were distressed at the time it had taken for a charge to be laid, but it was a relief that something was happening.

The feeling was still bittersweet though, she said.

"Even though it's going to court, it's still not going to bring Tevita back to us."

As well as Kava's daughter, his sister, Mary-Rose Telua, had also struggled with his death.

"They were like two peas in a pod. She went into shut down. She's doing all right now."

Speedy's own mother - who treated Kava like a son, as Speedy had treated him like a brother - became emotional when she heard Red Boats had been charged.

"It's the first time I've seen her break down since it happened ... we lost our brother, that's the hurting part."