“Some cemetery visit — I feel like a prisoner,” Ms. Joseph said.

The gazebo visit marked the closest she has ever come to visiting Tomika’s grave — a five-minute walk away, according to the maps given to Ms. Hunt. The officers were cordial but firm in telling Ms. Joseph she was permitted to pay her respects only from the gazebo.

The sole visible references to the burials on the island were some small religious statues left by city workers near the ferry dock, and a headstone at the gazebo bearing a cross, a prayer and the words “City of New York, Potter’s Field.”

Like the other seven women, Ms. Joseph said she was angry that the agency would restrict them to one visit apiece to their children’s graves, and would permit each woman to bring along only one person — a relative or a clergy member. The women would also be subject to Rikers Island visiting rules regarding permissible items, which means no cameras, phones, flowers or other mementos.

“They make it so that visiting your dead child in a cemetery is the same as visiting a prisoner in Rikers Island,” said Mr. Taylor, the lawyer. “That’s how the Department of Correction treats these women, who didn’t do anything wrong, and whose children didn’t do anything wrong.”

Ms. Joseph said her wish was for Tomika to be disinterred and reburied in her own plot in Calverton National Cemetery on Long Island, which she acknowledged, given all the time passed and the missing records, might be impossible “under that pile of all those tiny, deteriorating coffins.”

Still, she said, the most important thing was that she would soon have the opportunity to kneel at her daughter’s grave.

“I wasn’t able to be there when she died, so it’s very important to me to get to her final resting place,” she said. “I want to see where she’s buried, simple as that.”

She boarded the ferry back to the land of the living, while behind her on Hart Island, the backhoe kept on digging.