TORTOLA, British Virgin Islands — When visiting the Spock household, bring a swimsuit.

At 88, America’s top baby doctor gets in his daily swim, and has plenty of snorkeling gear for visitors. On land, Dr. Benjamin Spock is working on a new book and becoming increasing moralistic about child-rearing.

“I’m ready!” Spock yelled to his wife, Mary Morgan, who already was knee-deep in the aqua waters outside their bayside condominium one sunny Saturday afternoon, feeding bread to a pet grouper.

Spock splashed into the Caribbean, adjusted his face mask, then began swimming toward his 35-foot sloop, the Carapace, anchored about 200 feet offshore.

Spock has appreciated the sea since his youth in Connecticut. While at Yale, he won a spot on the U.S. crew team, taking a gold medal at the 1924 Olympics in Paris.

As a young pediatrician in Manhattan, he kept a 12-foot sailboat moored on the Hudson River or on Long Island Sound; as a medical administrator at the University of Pittsburgh, he spent evenings building a boat. While directing a university medical program in Cleveland, he’d take his boat out on Lake Erie and haul it to Cape Cod for summer vacations.

From his retirement in 1967 until last year, he lived on sailboats near Camden and off this sparsely populated British Virgin Island. He reluctantly moved onshore for health reasons, but he spends much of his time on his shaded seaside deck or at a writing desk facing the water. He still spends winters in the Caribbean and summers in Maine.

“I feel like all my life has been on the sea,” said Spock, as he eased his thin, 6-foot-2 frame into a deck chair. About 100 feet away, a pelican dived into the bay for a fish.

Spock, author of “Dr. Spock’s Baby and Child Care” and a longtime peace activist, rose that day before 6 a.m., accompanying his wife to market for fresh vegetables. He returned to work on his book, and she went to a neighbor’s farm, where she slopped the hogs in exchange for some okra.

The okra, breaded and fried in sesame oil, was later served for lunch with homemade cornbread, rice and a leafy salad — part of the couple’s macrobiotic diet. The 7-month-old diet, as well as exercises and meditation, are intended — as his wife put it in her native Arkansas twang — “to keep Ben around here a lot longer.”

“I’ve had at least six friends here tell me, `Say, you look well.’ I’ve lost my beer belly and haven’t been sick a day since I started in September,” Spock said.

Since then, he’s done a publicity tour to promote the sixth revised edition of “Baby and Child Care,” published last month; renewed work on his next book, “A Better World for Our Children”; and been host to a screenwriter after Disney signed an option to make a movie of his life.

Spock returned to Maine in mid-May. Earlier this month he spent 10 days in Cleveland, overseeing a phase of a three-decade-old study on child rearing that he began while working at Western Reserve College, now part of Case Western Reserve University.

He says he is growing increasingly moralistic about child-rearing, urging parents not to show hesitancy to their children about bedtime or other home rules. He believes parents should cultivate their children’s desire to be helpful, and push them not to compete, but to serve as tutors, counselors or other volunteers.

Spock, who said he envies people who have strong religious beliefs, emphasized the role parents must play in giving their children strong values. “I’ve come to the realization that a lot of our problems are because of a dearth of spiritual values,” he said.

On practical matters, he opposes disposible diapers (bad for the environment), Little League (too competitive), sunbathing, infant walkers and sugar-coated cereal.

Spock sees his life in three phases: the struggling pediatrician, the successful author and medical researcher, and the peacenik, anti-nuke activist and presidential candidate.

With a then-rare combination of pediatric and psychological training, he entered practice during the Great Depression, and said it took him three years to earn enough to pay his rent. Struggling to reconcile Freudian psychology with what mothers told him about their babies, he spent three years writing “Baby and Child Care.”

The book was a huge success when published in 1946. It since has sold 40 million paperback copies and has been translated into 39 languages, according to the publisher.

“Without that book,” Spock acknowledged, “I’d have had to have worked as a practitioner until I died.”

Instead, he developed theories on thumb-sucking, toilet training, punishment and discipline. After retiring in 1967, he gave 800 college lectures in the next eight years, most against the Vietnam War and levels of military spending.

In the latest edition of the book, he and co-author Michael Rothenberg urge parents to vote and to support better health-care and education in a world of discrimination and homelessness.