JACKSONVILLE, Fla. >> Robert Johnson, who turned 100 in early July on a hot and sunny Florida day, barely hesitated when asked what he’d do if given another chance to go to Antarctica, the land of eternal ice and snow that he first journeyed to as a teenager.

“It would be very tempting, it would,” he said. “That place stays in your heart. It really does.”

At 19, Johnson was the youngest member of Adm. Richard Byrd’s 1939 expedition to Antarctica aboard the USS Bear, a 19th-century, thick-hulled wooden ship with sails and diesel.

He went back with Byrd in 1946 for Operation Highjump, then joined another U.S. Navy expedition there, Operation Windmill, in 1948.

The son of a chief warrant officer in San Diego, Johnson was a Sea Scout who trained on sailing ships as a teen.

The summer he turned 16, he was one of the Sea Scouts aboard the Pacific Queen, a 300-foot square-rigger, for what was supposed to be a 15-day cruise. The becalmed ship ended up at sea for 67 days, its crew living on severe rations, creating headlines as a frantic search ensued.

That experience didn’t keep him from the sea: He joined the Navy two years later on a battleship and then volunteered for Byrd’s expedition. With his sailing experience, he was signed on to the Bear, bound for Antarctica.

He’s believed to be the last survivor of any of Byrd’s pre-World War II polar journeys, which caught the public imagination and made the explorer a much-decorated national hero.

Johnson, in fact, is most likely the last living member of any prewar polar expedition by any country, said Glenn Stein, a polar and maritime historian from Apopka.

Stein came to Jacksonville for Johnson’s 100th birthday party, which was under a tent outside his East Arlington home, attended by pandemic-masked family members and friends.

Five police cars drove by, sirens blipping, and neighbors and friends drove by as well, holding signs of support. The police officers then visited Johnson as he sat in his driveway near some food and displays.

Stein has interviewed Johnson several times and marvels at his still-sharp memory.

“He’s a treasure, an absolute treasure,” said Stein, author of “Discovering the North-West Passage: The Four-Year Arctic Odyssey of H.M.S. investigator and the McClure Expedition.” “This is a time when things like this just aren’t done any more, this kind of adventure.”

Harvey Morrissey, 16, a Sea Scout from Ocala, also came up for the party. He had done a podcast with Johnson and was struck by his vivid stories of Antarctica and of his teenage sailing journey on the Pacific Queen.

“That’s crazy,” he said. “I don’t think any Sea Scout today could do that. It’s a different world, compared to today, obviously.”

Johnson was in the Navy from 1937 to 1956, ending up at Naval Station Mayport as a chief bosun’s mate. He then worked for the Postal Service until 1990.

He recalls that on the first expedition, their transport on the ice was sleds and dogs. To feed the dogs, they would shoot a seal — and that would be the dogs’ lunch.

In Operation High Jump, he parachuted to the ice, making a heavy landing in what seemed to him the quietest place on Earth.

There’s a whole room in Robert and Mildred Johnson’s house dedicated to his three Antarctic adventures. He calls it the chief’s quarters, and it’s decorated with photos, awards and memorabilia.

A place of honor is reserved for Polar Penguin Pete, a penguin Johnson took with him after one expedition and then had stuffed. It’s been with him ever since, a reminder of his journeys to the bottom of the Earth.

“That’s quite a place,” he pronounced, some 72 years after his last trip there. “It’s different from anything else, that’s for sure. It is a wonderful place down there.”