WELLINGTON, New Zealand — Everest conqueror and Antarctic explorer Sir Edmund Hillary has returned to the frozen continent -- at age 87 -- for what he believes will be his last time.

Hillary joined New Zealand Prime Minister Helen Clark and other dignitaries who flew to Antarctica for the 50th anniversary of the Scott Base, which the adventurer helped build in 1957.

"This is probably the last opportunity that I will get to visit the wintery south," Hillary said Friday, the day after he arrived.

Hillary helped lead a team to the South Pole in 1955. He was the first person to drive to the pole, using a modified farm tractor.

The trip came two years after Hillary and sherpa Tenzing Norgay became the first people to climb Mount Everest, the world's tallest peak.

Hillary, who still travels widely to Nepal and elsewhere, last visited Antarctica two years ago.

"I was always prepared to come back one more time," said Hillary, whose comments were reported by New Zealand media traveling with the anniversary delegation. "I don't think it'll ever happen again, but this is a marvelous return."

Hillary criticized Japan for its policies allowing whaling for scientific purposes, and for pushing to revoke the international ban on commercial hunting. The Japanese whale hunting season began recently in waters at the far south of the world.

"They just don't seem to have accepted that these creatures, wonderful creatures that they are, should be carefully protected," Hillary said.