Michael Phelps and his wife announced the birth of their second child on Tuesday afternoon.

Phelps, the most decorated Olympian in history, and his wife, Nicole, said on social media that Beckett Richard Phelps was born on Monday.

"We had a healthy baby boy and a healthy mama," Phelps wrote. "I truly do feel like the happiest man in the world."

Magical moments yesterday... Nicole and I would like to introduce Beckett Richard Phelps to the world! We had a healthy baby boy and a healthy mama. I truly do feel like the happiest man in the world. Being able to build our family to now 4 (6 with doggies) is so incredible! #familyof4now

A post shared by Michael Phelps (@m_phelps00) on

Beckett joins Michael and Nicole's son, Boomer, who will turn 2 later this year.

The Phelps household includes French bulldogs -- 7-year-old Juno and 2-year-old Legend.

For both of his children to be born here makes Arizona much more to Phelps than a place he came to train for his final Olympics because long-time coach Bob Bowman took a job at Arizona State, or where he came for his life-changing rehabilitation in the fall of 2014 after a drunk driving arrest.

Phelps still swims to stay in shape, sometimes at ASU, but with no plans to return for a shot at the 2020 Tokyo Olympics.

"It's a peaceful thing for me to do," Phelps told azcentral sports' Jeff Metcalfe earlier this year.

"In 2012, I don't think you could have paid me to get in the water. It's one of the few places I can be really alone and I'm able to think and escape from everything."