“I was one of the lucky ones who was blown up into the air, and I fell into the sea,” Mr. Stoliar said. “When I came to the surface, there was nothing except a tremendous amount of debris and many, many people swimming in the water. It was very, very cold, and we had a hard time moving our feet and our hands.”

Mr. Frantz and Catherine Collins later recounted the sinking in a 2003 book, “Death on the Black Sea.” Mr. Stoliar told them he saw people screaming and thrashing in waves strewn with kindling. Many were clinging to a partly submerged section of the wooden deck, with cables and twisted metal from the ship’s railing attached to it.

He swam to the group, still clad in his heavy leather jacket, grabbed the railing and looked about at the terrified faces, shivering and sobbing in the cold. There was nothing to do but hang on. Hours passed and the cries gradually faded as people succumbed to hypothermia and exhaustion. Some floated off, others slipped into the deep.

One man lost his grip, grabbed Mr. Stoliar by the collar and dragged him under. But Mr. Stoliar broke free and regained his hold as the man sank out of sight. Soon birds appeared, flying over the corpses. As the dead drifted away, the decking grew lighter and rose in the water. Mr. Stoliar, a strong youth, dragged himself on top.

In the afternoon, the Struma’s first mate, Lazar Ivanof Dikof, floated by on a door. Mr. Stoliar pulled him onto his raft of wreckage. He told Mr. Stoliar of seeing the torpedo’s approach. In the numbing cold, they were surrounded by floating bodies. No one else appeared to be alive as night fell, and in the morning Mr. Dikof, too, was dead.

Alone now, Mr. Stoliar thought of giving up. He took out a jackknife to slit his wrists, but his fingers were too numb to open the blade. A short while later, about 24 hours after the Struma had sunk, a large ship appeared in the distance. He waved frantically, and saw figures on deck waving back.