En route to two meets next week in Australia, he stopped in New Zealand for research and development work at the University of Otago. His strokes and body specifications are being gauged in one of the world's most accurate flumes. The data will be used to design the custom swimsuits Phelps will wear next summer, when he tries to make Olympic history.
It is sophisticated business - and a long way from his family's introduction to the sport.
Before high-tech Speedos, there was a hungry little girl, a sister competing in a floral print suit with frills and one shoulder strap. Before that, there were teen-agers hanging out at a municipal pool in a Western Maryland mill town.
Phelps is expected to be a focal point of the 2004 Olympics in Athens, Greece. He is attempting to become the second man to win seven gold medals in one games - or perhaps the first to win five in individual events. That quest has followed a methodical progression, but it is not without paradox.
The 18-year-old rules a country club sport, but traces his family tree to a blue-collar community.
Phelps never heard a horn sounding a shift change, but by age 4 he was familiar with the demanding rhythms of his sport, one that led his family to relocate.
He is living a dream, but one sister's Olympic aspirations turned into a nightmare.
Phelps has acknowledged that his parents passed on good genes and a serious work ethic, but he hasn't spoken to his father since June.
Regardless of his current family dynamics, Phelps understands it wasn't luck or random occurrence that placed him on the path that made him the fastest all-around swimmer ever.
"Being able to see my two older sisters grow up with swimming and dedicate themselves to the sport, it's a different environment," Phelps said. "I grew up around the pool, I was always around the pool. If I didn't have that, I wouldn't be here today."
To find Phelps' roots, drive west on Interstates 70 and 68, past Hagerstown and Cumberland, down State Route 36 to where George's Creek flows down a valley into the Potomac.
Debbie Phelps, Michael's mother, was raised in Westernport, population 2,129. Fred Phelps, his father, grew up a mile away in Luke, which had 80 residents in the 2000 census. Piedmont, across the Potomac in West Virginia, completes the "Tri-Towns."
Debbie's father, a good soccer and baseball player in his day, had his own contracting business; Fred's was a chemical engineer at the paper mill now operated by MeadWestvaco. It employs 1,350; nearly 2,500 worked there in the late 1960s.
"Luke used to have 250 people," Fred said during a visit there on a dazzling autumn day. "Somebody dies and the plant buys the property. They'll buy up everything, so they won't have to pay taxes. That's the mill you smell, but the locals will say that smells like bread and butter. I used to know every person and every house in town. There were three seasons: football, hunting and fishing."
In 1986, Allegany County closed Bruce, the high school in Westernport. Students were sent north to Lonaconing, where there is a monument to favorite son Lefty Grove, the late Hall of Fame pitcher who won 300 games between the two world wars. The consolidated school was given the name Westmar, but now it, too, might close.
The stadium behind what is now Westmar Middle is used by rec teams, but it was a livelier place when Fred played football, basketball and baseball for the Bruce Bulldogs.
One of the older wiseacres was Leo Mazzone, now the pitching coach for the Atlanta Braves. Interscholastic athletics for girls were not offered, but Debbie competed during school field days and worked the sidelines as a cheerleader.
"On Friday night, everyone in the community was at the high school football game," Debbie said. "It was a wonderful place. There was a municipal pool in town. You went there in the summer to sunbathe."
Fred was a 165-pound defensive back in high school, but went 190 as a college freshman. He said he didn't need the extra weight to leave an impression.
"I liked it when the running back and receivers heard footsteps," Fred said. "I liked it when the guards and tackles pulled so you could hit the biggest guy out there."
At Fairmont State College in West Virginia, Fred studied physical education and set school records for interceptions in a season and, after he was steered to track and field by a football assistant, the triple jump.
In the 1968 Bruce High yearbook, listing the place where he would most likely be found, Fred listed the street where Debbie lived. A year behind Fred, she followed him to Fairmont State. They married in May 1973.
Fred also went to work in the public sector in 1975 when he joined the Maryland State Police. He was on call with a tactical assault unit for 11 years, but Sgt. Fred Phelps has spent most of his career on the interstates, inspecting commercial vehicles.
Debbie was named a Maryland Teacher of the Year in 1994 and again in 2000. She is an assistant to the executive director of public schools in Baltimore County, monitoring achievement at 33 schools in the Southwest District.
As they settled in Harford County and started a family, Fred and Debbie determined that the television would never serve as a baby sitter.
"From my and Fred's point of view, we wanted our children to be well-rounded," Debbie said.
"One thing that Debbie and I decided," Fred said, "is that the kids were not going to hang around a mall or get involved in things they shouldn't."
Hilary was born in 1978, Whitney two years later. Michael Fred Phelps II came along in 1985.
The girls tried Brownies, ballet and baseball, as Hilary was registered to play with the boys one spring. Her potential was noticed at the North Harford Swim Club by the family pediatrician. Dr. Charles Wax had taken his own children from that grass roots setting to more demanding year-round clubs.
Competing in that frilly suit purchased in the children's section of a department store, sans goggles or cap, Hilary earned a runner-up trophy at a local meet in 1986.
But she wanted the big one and moved on to a more ambitious club in Bel Air. She then joined the North Baltimore Aquatic Club, and the logistics involved in commuting to symbolized the family's commitment to swimming.
"When we started, my dad would be up at 4 a.m. on the mornings I had 5:30 practice," Hilary said. "As Michael got older, my mom would drive all day Saturday, going from his games to our practices and back."
The family built a custom home in Whiteford and shuttled 10-year-old Hilary to those double sessions, at the Meadowbrook Aquatic Center or Loyola High School. They weren't in the house long. The family moved to Towson in 1990 to be closer to the NBAC.
"We built a brand new home on five acres in northern Harford County, but we were never there," Debbie said. "We were all never home at one time in that house. I remember sitting at a desk at Loyola, one girl eating pizza, another doing homework. You hear about ice skaters relocating or kids moving in with coaches, but they were not going to move without us."
"I loved it up there [in Harford County]," Fred said, "but there was too much travel. Moving was better for the kids."
Cutting out the commute was not a cure-all. In 1993, Fred and Debbie separated. A year later, they divorced.
"It was like a storybook [marriage], but sometimes chapters go in different directions," Debbie said. "We were close, but we grew apart."
Michael won awards for baseball and lacrosse. He talked wistfully of playing football as a freshman at Towson High in the fall of 1999, but within a year he would be at the Olympics, fueled by talent, training and drive.
"Failure to him was totally unacceptable," Fred said. "If he didn't do his absolute best, he was totally angry."
As his sisters progressed through the ranks of the NBAC, the boys in their training group found their way to the Phelps home. Hilary credits Troy Pusateri for dubbing Michael "Little Phelps."
Michael is the youngest male ever to set a world record in a stopwatch sport, and Fred points to the company of older boys as one reason his son achieved so much so young.
"My sisters swam with older guys, who were always hanging around the house," said Michael, who lives with his mother in Rodgers Forge. "When I got to this group [the senior elite group], I was 11. Some of the guys were 17, but I was used to being around them. I wasn't intimidated."
The sport earned Hilary a scholarship to the University of Richmond, where she set several school records. In her final meet, the Colonial Athletic Association championships in 2000, Michael sneaked on to the deck to flip her lap counter through all 66 laps of a 1,650-yard race.
She is 25 now, works for a firm in Washington that does public relations and political consulting, and has been confused with Michael's girlfriend from Sydney to Security Square Mall.
Hilary was a good age-group swimmer, Whitney a great one. Michael missed the start of his sophomore year at Towson for the 2000 Olympics. Whitney missed the first week of her freshman year there to go to Rome for the 1994 world championships.
At age 14, she was the national champion in the 200-meter butterfly, the same event that would bring Michael his first international acclaim.
Whitney won her national title in 2 minutes, 11.04 seconds, but never got faster. In retrospect, NBAC coach Murray Stephens recalls a red flag being raised in the fall of 1995 when he placed a "monofin," a training apparatus, on Whitney and she complained of back pain.
She went to the 1996 Olympic trials as the fastest seed off her 2-year-old best, but in the interim two bulging discs and a pair of stress fractures cut into her form.
"I just pounded through it," Whitney said. "I didn't want to be a wimp. ... I wouldn't get out of the pool, even though I was injured. It came to the point where I didn't want to think about the fact that I was injured."
Racked by doubt and pain, Whitney finished sixth at the 1996 trials. Five months later, she finished second at the summer nationals with a time that would have won the trials in Indianapolis.
She returned to that pool to see her brother qualify for the 2000 Olympics and star in the Duel in the Pool last April, when her anguish was evident.
Has her disappointment from 1996 abated?
"It has, but I don't enjoy being around the pool," Whitney said. "I don't enjoy watching swimming. I enjoy watching my brother compete, but if I could have watched him swim [at the Duel in the Pool] and then left, that would have been fine. I really didn't want to sit there for the entire meet.
"I used to kill Misty Hyman [the 2000 Olympic gold medalist]. It's frustrating to think, if I could have trained, how fast I could have gone. That's one of the reasons why I don't like to go to meets."
Her Olympic trials experience is the elephant in the room that isn't confronted.
"I didn't know what to say to her," Debbie said of 1996. "The Christmas before, B.J. [an uncle] gave Whitney a 1996 Atlanta [Olympics] mug.
She said: 'I'm going to be there.' I thought she was going to be there, too. She should have been there, but she was injured and she wasn't telling anybody. ... People were sending cards to the house. It was like someone had passed away."
Whitney doesn't want any sympathy.
"Don't feel sorry for me," Whitney said. "Just understand. I don't think she [her mother] understands the pain. I don't think she understands how much that injury hurt, emotionally and physically."
Whitney, 23, accepted a scholarship to the University of Nevada Las Vegas, competed sparingly there as a freshman and sophomore, then ended her career. She returned to the area in late summer, lives with her father and stepmother, Jackie, in Linthicum and is in the management training program of a rental car company.
"I don't like to discuss swimming with him," Whitney said. "I look at him as my little brother, someone I used to wake up in the morning, fix him breakfast, get him off to the school bus. We did kid stuff. I see more to him than just Olympic star. Fame doesn't make him who he is."
Father and son, both proud men, one 53 and the other 18, have not spoken since Michael's high school graduation party. Whether real or perceived, slights had been simmering.
Fred remarried one week before the 2000 Olympic final in the 200 butterfly. He and Jackie went to Sydney, where Fred had a pep talk with Michael after the semifinals. They went to the Duel in the Pool, but not to Barcelona for this summer's world championships, where Michael's status covered some of the travel expenses for Debbie and Hilary.
Overseas trips are costly, but Fred also did not go to the U.S. Summer Nationals in College Park last August.
Both say calls to the other have not been returned.
"There are reasons, and I really don't want to get into that," Michael said, when asked about being estranged from his father. Pressed, Michael said: "He didn't call me after I set my first world record [in 2001]. He didn't call me after Barcelona."
"Two days after he graduated," Fred said, "he said he didn't want me to go to Barcelona because I hadn't been around. This is his world, and I'm just watching him travel through it. People ask me how he's doing, where he's swimming next, and it's hard to say that I don't know."
Proof of his remarkable focus, Michael was sharper than ever this summer, when he produced seven world records in 41 days. Five came in Barcelona, which led Speedo to extend his suit endorsement contract into the most lucrative ever.
The youngest U.S. male swimmer ever to turn professional, Michael bought his mother a 2003 BMW last Christmas.
No family members will watch Michael in Australia during Thanksgiving week, but when Debbie is at a meet, she is in the public eye nearly as much as her son.
Swimmers prepare to race in a ready room, out of sight; family members squirm in plain view. Swimmers' faces are obscured during competition, and in Barcelona the large video screen often included reaction shots from Debbie.
Mindful of what can happen to Olympic hopes, she tries to shield her emotions.
"Every time Michael gets on that block, people expect him to do something spectacular, and that's hard," Debbie said. "I'm trying to keep calm, but I have no control over what goes on in the pool. I try to be cool, calm and collected on the outside. Am I that way on the inside? No. I am not."
Sun staff researcher Jean Packard contributed to this article.