Marathon swimmer Diana Nyad dropped into the water off Havana about 7:45 p.m. Sunday to begin a 103-mile swim to Key West, Fla., in an effort that is expected to take 60 hours.

Nyad, 61, who has been training for this effort for two years, is hoping to set a record for open-water swims without a shark cage. Originally, she had planned to make attempt the swim in 2010. But poor weather conditions thwarted that plan.

This time the conditions — still air and flat water — appeared to be perfect, she said, according to The Associated Press. “I don’t believe much in destiny,” Nyad said before beginning the swim, “but you have to take what you can get, and this is what I dreamed of: a silver platter.”

Matt Sloane of CNN, who is covering the swim from one of the support boats that is with Nyad, marked the beginning of the swim with this post on Twitter:

745p ET – @Diananyad jumped the water at Marina Hemingway in #Havana to start the #XtremeDream swim, and swam off into the sunset!

At a news conference earlier in the day, Nyad said that she was confident and that she hoped people in her age category would be inspired by her effort. “I also want it to be a moment for thousands, and I dare say millions of people my age, who are going to look and say, ‘60!’” she said. “The joke is 60 is the new 40, and it’s true. We are a younger generation than the 60 that went before us.”

She also said she hoped her swim would help to increased understanding between the United States and Cuba. “I’m under no delusion that my swim is going to make any new political ramifications,” she said. “But it is a human moment between the two countries.”

Although Nyad called open-water distance swimming marathons of “sensory deprivation,” this is far from a lone effort. She is being accompanied by five boats carrying her support team, and six kayakers are taking shifts alongside her paddling kayaks equipped with electronic devices to repel most species of sharks, according to CNN. In addition, specially trained divers are at the ready to deter any sharks that may not be repelled by the electronic devices. She will stop periodically to drink fluids and eat small amounts of food.

CNN.com has a map showing her progress and is tweeting about her swim.

A little after 9 a.m. on Monday Sloane reported that Nyad had covered about 20 miles and was “swimming strong,” despite a few shoulder pains.