# 38 people took the same virtual dive on land and underwater, but floating in the pool made the imagined journey feel much longer

> Thirty-eight people ended this experiment with two different internal maps of the same virtual trip. Everyone watched the same underwater VR dive, yet the group floating in a pool judged that they had traveled farther than the group who stood on solid...

Canonical URL: https://www.argo.net/38-people-took-the-same-virtual-dive-on-land-and-underwater-but-floating-in-the-pool-made-the-imagined-journey-feel-much-longer/
Byline: ARGO.net Editorial Team
Published: 2026-08-03T07:50:02+00:00
Categories: Explainer, Humans

![Person enjoying a virtual reality gaming session with a VR headset and controllers](https://www.argo.net/wp-content/uploads/2026/08/underwater_virtual_reality_headset.jpg)

Thirty-eight people ended this experiment with two different internal maps of the same virtual trip. Everyone watched the same underwater VR dive, yet the group floating in a pool judged that they had traveled farther than the group who stood on solid ground. A [Scientific Reports study](https://www.nature.com/articles/s41598-020-80100-y) published on January 13, 2021, treated that gap as a change in **vection**, the felt sense of moving through space when the motion is largely driven by sight.

Underwater VR is the visual hook, but the central finding belongs to psychology. The study asked whether **water immersion** could alter **self-motion perception** by stripping away some of the ordinary body cues that say, with complete certainty, that a person is standing still. Floating weakens pressure from the feet and changes how the body senses support, so the moving visual scene has a better chance to dominate the final judgment. In ordinary headset use, the floor, the ankles and the rest of the support system keep sending a steady message that the body has not gone anywhere. Pool immersion softens part of that message without adding a motorized platform.

Earlier VR work often treated stronger vection as a trade that might come with greater discomfort or a stronger feeling of simply being inside a digital world. The pool result stayed narrower and more interesting than that. Participants in water reported larger traveled distance, yet the paper did not find a difference in visually induced motion sickness or in **presence**. That combination makes the result easier to interpret: the pool seemed to strengthen perceived motion itself, rather than just making the whole experience feel more intense in every possible way.

## Why floating changed the feeling of motion

Vection depends on how the brain weighs signals that do and do not agree. Vision may say that the body is gliding forward, while the soles of the feet, the joints and the vestibular system report a quiet body on a stable surface. The authors argue that floating removes part of that contradiction. In water, the body loses its usual contact with the ground and the visual story of forward travel can carry more of the decision.

The abstract reports the key behavioral result in plain form: participants in the Water condition gave larger judgments of self-displacement than participants in the Ground condition. The article does not need to overreach beyond that sentence. A bigger distance estimate means the floating group accepted more of the visual motion as their own motion, which is exactly what a vection experiment is trying to measure.

**Géraldine Fauville** and colleagues also place the result inside a larger history of vection research. Illusory self-motion has been studied for well over a century, often with rotating drums, moving visual fields, or headset-based scenes. Pool immersion adds a simple twist to that tradition. Instead of changing the video, the team changed the body state that surrounded the video and that was enough to shift perception.

## How the pool experiment worked

The design was deliberately direct. One group experienced the VR sequence while standing on land. The other group entered the pool, floated horizontally with the head underwater, breathed through a snorkel, wore a flotation belt and stayed connected to an elastic tether fixed to an anchor on the pool floor. Both groups were exposed to the same **OceanDIVR** content, so the critical difference was the physical setting rather than the imagery. The tether mattered for consistency as well, because it kept swimmers aligned with the setup and reduced the chance that free drifting in the pool would become the real source of the distance judgment.

Researchers also kept the distance-estimation task consistent across conditions. Before the experience began, participants were shown a mark about 15 meters away in the relevant setting and were told that this was the starting point for the VR activity. When the sequence ended, each person estimated how far they had moved from that start. The paper treats that report as its main behavioral readout, which makes the study easier to follow than work that relies only on abstract scales.

**Stanford University**, **Iowa State University** and the nonprofit diving education group The Hydrous all appear in the author list and affiliations and the team used a custom **DIVR headset** to make the underwater setup possible. The method was unusual, yet it stayed controlled in the ways that count most for interpretation. A person on land and a person in water saw the same scene, answered the same kinds of questions and reached the result through one clear point of contrast.

## Why sickness and presence stayed level

Motion sickness is the obvious worry in any study that tries to make visual motion feel stronger. If water had simply made the scene more overwhelming, the outcome might have shown up as higher discomfort scores as well. The paper says that did not happen. No difference appeared between conditions on visually induced motion sickness, which means the stronger self-motion judgment in water was not paired with a measured rise in nausea or disorientation in this sample.

The same restraint applies to presence. Presence is the psychological sense of being inside a virtual setting and the methods section says it was measured with six questions. Even with the head underwater, a snorkel in the mouth and the body floating in a pool, the water group did not score higher than the ground group on that dimension. A matching PubMed [record](https://pubmed.ncbi.nlm.nih.gov/33441803/) summarizes the same point, which helps confirm that the null result belongs to the core finding rather than to a minor detail.

**Visually induced motion sickness** and **presence** matter here because they narrow the explanation. A broad rise across all subjective measures could mean participants were simply more excited by the pool setup. The narrower pattern suggests something more specific: water helped the moving image convince the perceptual system that the body had traveled farther, while the wider emotional and comfort profile remained relatively stable.

## Where underwater VR could be useful

Possible applications follow naturally from that narrow pattern. Training designers, educators, or simulation researchers might want stronger self-motion without paying for larger moving platforms or more complicated motion rigs. If floating can raise vection with the same visual content, then a pool can function as a low-mechanical way to study how people judge movement, route length, or spatial travel in immersive scenes.

Marine education is one likely fit because the content already matches the body posture and surroundings of the user. The Stanford [Virtual Human Interaction Lab](https://vhil.stanford.edu/) has explored ocean-facing immersive work for years and this paper gives one reason underwater delivery may feel distinct from ordinary headset use. A diver, student, or trainee may not need a larger screen or a faster animation if the physical environment already reduces conflicting support cues.

Several limits keep the story in proportion. The final sample was small, the task measured judged travel distance rather than real navigation skill and the study did not prove that every underwater VR experience will feel better or teach more. The setup also focused on one underwater scene and one bodily posture, so the same effect size may not appear with a faster sequence, a different field of view, or a user who is less comfortable breathing through a snorkel. It showed one durable point instead: when 38 people took the same virtual dive on land or while floating underwater, the pool increased perceived self-motion, while sickness and presence stayed statistically similar across conditions.