Michael shared that Boomer is "relaxed" in the water.
Photo: Michael Rozman/Warner Bros
2/5
Michael showed Boomer his personal swimming pool, gifted to him by Ellen.
Photo: Instagram/@m_phelps00
3/5
Boomer showed off his latest milestone with the help of his puppy brother.
Photo: Instagram/@boomerrphelps
4/5
Michael and Boomer have been enjoying some post-Olympics retirement.
Photo: Instagram/@m_phelps00
5/5
Michael shared that he is the one responsible for updating Boomer's Instagram account, which has over 700,000 followers to date.
Photo: Instagram/@boomerrphelps