There are few things more exhilarating than jumping into cool water on a hot day.
These are beautiful moments we not only cherish but continue to long for our entire lives. So imagine what it's like to be denied that joy.
Scars in our society are hidden in the most unusual places.
"I think that my work has really reshaped how the public understands swimming as an issue of social equality, social justice and social inequality," said Professor Jeff Wiltse from the University of Montana and author of "Contested Waters."
He is a rare expert on the racist history of swimming. A conversation with him opens our eyes to the dark side of something that is usually seen as bright and joyful.
From the beginning, he squashes a common fallacy: Black people aren't physically built to swim.
"During the 19th century, people of African ancestry were more accomplished swimmers than people of European ancestry. They were more likely to be swimmers and more likely to be better swimmers."
It's what happened in the 20th century that changed everything.
"There were thousands of public swimming pools that were built in the United States during the 1920s and 1930s," he said.
It was a swimming revolution. At a time when there was no air conditioning, people suddenly had a way to find wonderful relief from the heat - but not everyone.
"The vast majority of these pools were for whites only. And the Jim Crow pools that were accessible to black Americans tended to be small and much less desirable," Wiltse said.
For generations, the public swimming pool became a classic example of white supremacy. Even though pools were funded by government money, hardworking, tax-paying minorities across the country were not allowed.
Even as courts started ordering public pools to be made available to all people, our society continued to evolve in hateful ways.
"There were literally tens of thousands of private club swimming pools that were developed in the United States during the 1950s and 1960s, almost without exception, these tens of thousands of pools were for whites only," Wiltse said.
And those public pools that were now integrated, were being shut down because white people refused to use them.
Swimming pools became battlegrounds. Chicago, Pittsburgh, Saint Louis were scenes of terrible violence where white mobs would attack any person of color who had the audacity to enter.
But perhaps the most significant confrontation was in St. Augustine, Florida, 1964, when African Americans and other protesters jumped into an all-white motel pool. What happened next has become an iconic moment in the civil rights movement.
"The manager of the pool poured acid into the water as a way to drive protesters out of the pool, which to my mind, reveals the viciousness of the sentiment behind objecting to interracial swimming," Wiltse said. "It caused a backlash against racial discrimination in a variety of forms."
One of the reasons this became "the moment" is because the architects of the civil rights movement showed up: Reverend Ralph Abernathy and Dr. Martin Luther King, Jr.
"We weren't allowed to swim with white children. They thought that we had cooties or something like that," said Donzaleigh Abernathy, Ralph Abernathy's daughter.
Donzaleigh Abernathy and her father Ralph were dear friends with MLK. In fact, it was King who taught Donzaleigh how to swim, but in a friend's private pool. Public pools were unavailable. She remembers St. Augustine, and how her dad and King knew it was time to fight.
"I know they were arrested in St. Augustine, and I know that they confronted the man who owned the Monson Hotel, and I think they were arrested there after confronting him," Donzaleigh Abernathy said.
It is now a famous photo. Two giants, in jail together, fighting for the right to swim.
Even Mr. Rogers would join the fight. In a beautifully crafted moment, he invites a black police officer into his tiny pool. Mr. Rogers and officer Clemmons were molding a new generation of thinking.
Sadly, tremendous damage has been done. African Americans now struggle around water due to a century of being denied.
"Swimming doesn't get passed down from one generation to the next. And instead, what has gotten passed down is actually a fear of water," said Wiltse.
If you want to understand how racism from the past continues to leave its ugly mark, listen to this:
A cool pool on a hot summer day may be pure joy from some, but not all. Hate from the past continues to pull us under.
And it's not just black. Pre- and post-World War II in Los Angeles, all people of color - Asian, Latino and Black - were not allowed into the public pools except for the day before they were cleaned. That says it all.
Watch all of our Faceism stories streaming now on our ABC7 Los Angeles app on Roku, FireTV, Apple TV and AndroidTV.