David Miller completed the 568 miles at Campolindo High School.
It's the same place the "Swim A Million" project first began in January, until the pandemic hit and the pool was forced to close.
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Because he worked there as a lifeguard, he was able to use the pool, but said he had to wear a wetsuit because they shut off the heater.
"I don't like swimming in the cold," Miller quipped.
Then came the summer and fall, when wildfire smoke blanketed Moraga for weeks at a time.
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"The smoke was worse than the cold," he said, not able to swim for several days.
But he pressed on, knowing that the effort he was putting into it paled in comparison to what cancer patients face.
The finish line was set for Sunday, Dec. 27, an end to a year-long journey. You can see his swimming goals and averages per month on his website.
The cause is close to his heart. He lost his father to lung cancer, and his mother and sister are both cancer survivors.
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"My father passed from lung cancer. My mom has survived three bouts of cancer. My sister has had cancer. A cousin, an uncle, an aunt, close friends. It seems like everyone I know has been touched or is dealing with cancer," he said.
Miller also met his fundraising goal, raising more than $50,000 for the Cancer Research Institute.