This article introduces a novel, ecological, obstructed walking paradigm. Gait adaptations to circumvent obstacles undergoing uncertain displacements, and the effect of revealing the obstacle’s action beforehand, were investigated in young adults. The personal space (PS) maintained during walking was quantified for the first time under different environmental factors including auditory distractions. Obstacle movement and its uncertainty resulted in gait adjustments aimed at gaining time to assess the situation. Early gait adaptations and constant clearances around the obstacle suggest that anticipation and preplanning are involved in such navigational tasks. Participants systematically maintained an elliptical PS during circumvention, but they adjusted its size according to different environmental factors. There was a relationship between the size of PS and level of attention, which suggests that the regulation of PS is used to control locomotion. This novel paradigm has important implications for the assessment and training of locomotor ability within real world environments.