It was all part of the 18th annual Swim Across America event in the city. Since it began, the San Francisco event has raised more than $6 million for UCSF Benioff Children's Hospitals in Oakland and San Francisco.
Participants swam 1.5 miles from Little Marina Green to Aquatic Park by Ghiradelli Square.
Each swimmer has been touched or affected by cancer in some way. They form teams to raise money together. The biggest team is named Team Susan Survives.
"Everyone is on my team. There are so many people that have joined over the years, there are even people that I don’t really know that just sign up and join my team, and I feel so honored that they want to be on Team Susan," said Susan Helmrich.
Helmich's story is inspiring, it's no wonder why everyone wants to raise money in her name.
She is a three-time cancer survivor. She was diagnosed with a rare vaginal cancer at age 21, lung cancer at age 42 and pancreatic cancer at age 53.
"Each time I used swimming as a way to get better and to prove that I’m not done yet," said Helmrich.
The last diagnosis stopped her from doing the swim that year, but since then every year she's participated.
"I’ll be 68 and I never thought I’d live this long and so my story is inspiring because I think it gives people hope that a cancer diagnosis is not always a death sentence. It’s terrible, treatment is terrible, getting though it is terrible, but you can come out the other end," she said.
Helmrich's story has pushed others to continue their fights, and even develop a love for swimming.
"I think it’s the most freeing thing I could ever do, especially open water swimming," said 16-year-old Maya Merhige.
The Berkeley High School student was inspired by Helmrich when she was seven years old.
This year just Merhige and Helmrich combined have raised more than $50,000 for cancer research. Team Susan Survives has raised nearly $130,000 this year, and more than $1 million since the event started in San Francisco.
Organizers are looking to Merhige as the future of this swim, encouraging more young people to get involved. Her next goal is to be the first teen to complete the Oceans Seven.
"It’s seven marathon swimming channels. I’ve done two of them, I’m doing the English Channel next summer and then there’s three more I’m hoping to finish before I’m 20," said Merhige.
Click here to donate to Swim Across America.