The ‘dry’ immersion (DI) is the well-known model of gravitational unloading used for studying the physiological effects of space flights on Earth. The prolonged muscle unloading is similar to its effect on the muscles unloading in microgravity. The changes in the vestibular system activity due to the sensory disintegration processes have also appeared. Here we summarized our findings of the influence of the 5-day and 21-day DI on the estimation of neutral stimuli and onto the strength of the Muller-Lyer and Ponzo visual illusions. The responses were registered in verbal and motor domains. The DI influence on the sensorimotor tasks was more pronounced than on the verbal one. It was shown that the strength of Muller-Lyer illusion registered by tracing and grasping tasks was modulated strongly by the DI time-course. It tended to decrease during DI while the use of a ‘Penguin’ suit that provided axial load or high-frequency myostimulation of muscles of both legs had restored its strength to the pre-DI level. We propose that hyperactivation of the dorsal pathway of visual processing can be one possible reason for such result patterns.