FILE: X-ray image of neck unrelated to study. (Credit: © IvicaNS - stock.adobe.com)
In A Nutshell
- Retired Navy commander Joseph Dituri said he came back about half an inch shorter after 100 days living in an undersea habitat, though his own figures varied.
- The evidence is one man, self-reported, with no control group and no standardized height measurements described in the published summary.
- Pressure has not been shown to cause the change, and ordinary daily spinal compression, posture and measuring method could each account for a fraction of an inch.
For his first couple of months in an undersea habitat, Joseph Dituri kept cracking his head on a screw sticking down from the ceiling. Then it stopped, and by his own account, the reason was that he had gotten shorter.
Dituri, a retired Navy commander, lived 100 days at roughly 1.7 times surface pressure and reported losing between half an inch and three-quarters of an inch of height. Whether pressure, ordinary spinal compression or something else explains it is a question that one man’s report cannot answer.
What Happened Beneath The Florida Lagoon?
Dituri surfaced in Key Largo on June 9, 2023, after 100 days inside Jules’ Undersea Lodge. The Associated Press and his own Guardian essay put the lagoon at 30 feet deep, while USF and Guinness World Records cited 22 feet for the habitat’s living depth.
In a WKMG interview published June 30, 2023, he said, “I shrunk about half an inch,” a figure USF’s release repeated. NPR quoted him saying he shrank “about three-quarters of an inch, give or take.” The Guardian essay, published in September 2025, also gave three-quarters. He wrote that the head bumps stopped after a couple of months and that he was back to 6 feet 1 inch seven or eight months after leaving. None of these accounts came from a standardized series of measurements.
Project Neptune’s team described the case in the Aspetar Sports Medicine Journal in November 2024. It followed a single 55-year-old man who began at 1.85 meters (about 6 feet 1 inch) and 100 kilograms (about 220 pounds), living at 1.67 atmospheres absolute while undergoing blood, urine, saliva, pulmonary, vision and psychological testing. That pressure matches roughly 22 feet of seawater under the NOAA Diving Manual conversion of 33 feet per atmosphere, consistent with Dituri’s own description of pressure about 70 percent above the surface.
Does Pressure Explain The Missing Height?
Not by itself. The Divers Alert Network explains that most tissues reach equilibrium with surrounding inert-gas pressure within about 24 hours. Pressure acts throughout fluid-filled tissues, and its most obvious volume effects involve gas-containing spaces such as the lungs, ears and sinuses. Indirect musculoskeletal effects from habitat life, movement, exercise or posture remain possible, but ambient pressure cannot automatically take the blame.
Astronauts offer a loose comparison. A 2020 NASA technical memorandum on a January 2018 workshop reported stature gains of as much as 3 percent in microgravity, and it did not support the simple idea that unloaded discs just swell. University of California San Diego researchers likewise found no consistent change in disc height among station crew. Spaceflight and a shallow undersea habitat load the body very differently, so neither result transfers neatly.
How Much Can Adult Height Change Anyway?
More than a single reading suggests. Spinal discs, which make up about a quarter of spinal height, lose fluid under daytime loading. A 2020 Scientific Reports MRI study of 25 healthy adults found that a disc signal tied to water content fell from morning to evening in the neck, mid-back and lower back. Its authors note, citing earlier work, that such changes may reduce spinal height by up to almost 2 centimeters, or about 1 percent of total body height, over a day. That study did not measure height itself.
For a man of about 73 inches, 1 percent is roughly 0.7 inch, and almost 2 centimeters is about 0.8 inch. A half-inch reading therefore sits inside the range that paper describes for ordinary daily variation, which makes measurement time, activity and technique hard to separate from any effect of the stay.
What Does The Evidence Actually Support?
Very little about causation. Dituri attributed the change to spinal compression, but his essay offers no data on that. A stronger study would need several participants, matched surface controls, calibrated measurements at fixed times, detailed posture and exercise records, and spinal imaging before and after exposure.
Dituri completed a record underwater stay and reportedly resurfaced shorter, but pressure, daily compression, posture, measurement differences or several factors together could each explain the missing fraction of an inch.
