Rudolf Hoess oversaw the deaths of almost 1 million Jews as the commandant of the Auschwitz extermination camp.

He likely never would have imagined that someday his grandson would be in the Jewish state, enjoying the Tel Aviv waterfront.

But Rainer Hoess, 48, is in Israel, and seems to be enjoying his trip.

He even tweeted a picture of himself standing above Tel Aviv’s marina Thursday, and described the location as “very nice.”

Hoess, who discovered his family history when he was 12 years old, has dedicated himself to fighting the rise of neo-Nazi movements in Europe and last week launched an informational campaign ahead of the EU elections, which kick off Thursday.

“Right-wing extremists are not stupid,” he said. “They are growing, gaining ground, very slowly but very effectively.

“I’m very aggressive against them,” added Hoess, who has turned down multiple offers to participate in neo-Nazi events.

“Every time I have the chance to work against them, I will do that.”

Entitled “Never Forget. To Vote,” the campaign launched by the Swedish Social Democratic Youth League (SSU) ahead of the May 22-25 vote sees the ballot box as the best defense against resurgent far-right extremism.

“To have Rainer at the front of this initiative is a way to show that he can never forget and we should never either,” SSU head Gabriel Wikstroem said.

Despite the disapproval of other family members, who preferred to bury their past, he has spent more than 20 years researching his background and the Nazi movement.

Hoess, who wears a Star of David around his neck, devoted the last four years to educating schoolchildren about the dangers of right-wing extremism.

What began when his children’s teachers asked him to share his story with pupils at their school has now become a full-time job that saw him visit more than 70 schools in Germany last year alone.

His aunt Brigitte, one of Rudolf Hoess’s five children, chose the opposite path.

Only last year, at the age of 80 and dying of cancer, she chose to share her story with The Washington Post, on condition that her married name and any details hinting at her identity be kept hidden.

Through his own research, Hoess has met many Holocaust survivors, even traveling to Israel to take part in a documentary — a delicate undertaking, he admits.

“It was a little bit tricky, as the grandchild of a mass murderer, to go to Israel.”

Rainer Hoess was a central figure in the 2011 documentary “Hitler’s Children,” which examines how descendants of key Nazi figures cope with the burden of their families’ actions.

One million Jews were killed at Auschwitz from 1940 to 1945 along with more than 100,000 non-Jewish Poles, Roma, Soviet prisoners of war, homosexuals and anti-Nazi partisans before the camp was liberated on January 27, 1945.

Rudolf Hoess experimented with different methods of mass killing, eventually settling on the use of the pesticide Zyklon B to gas his victims.

AFP contributed to this report.