"One of the reasons is because I wanted one enormous adventure in my life, and I love sailing," Thorndike, 56, told Correspondent Steve Price of CBS affiliate KFMB-TV in San Diego.
The trip started in San Diego on Aug. 4, 1996, and almost ended five months later in the Falkland Islands when Thorndike became sick.
"I never felt like turning around," she said. "But when I left San Diego, I have to be honest: I never thought I'd see it again. I just wasn't sure if I'd ever come back."
On her 36-foot boat, Amelia, Thorndike battled 50-foot waves, loneliness, and a major lack of sleep. But with the encouragement of friends who sent her emails, she continued her journey.
Her longest stretch at sea lasted 95 days from Argentina to Tasmania. Thorndike said that her trip on the ocean waters were well worth the difficulties.
As Thorndike pulled into San Diego on the final leg of her trip, she was all smiles and waves.
Her next challenge?
"I don't know," she says with a smile. "Go plant roses or something."