Environmental navigation is a key human behavior and precedes most other important human behaviors. While navigating, we use distance perception, the purpose of which is not to accurately estimate any given distance, rather to estimate the path that contributes to reproductive success. For many years no theory existed which could explain why people overestimate vertical surfaces, but not horizontal ones. The evolved navigation theory (ENT; Jackson and Cormack, 2007) considers that human perception is shaped by natural selection. Navigation costs, especially the risk of falling, are defined within the theory framework. Navigation costs shape distance perception so that the path with higher costs seems longer, which consequently reduces the frequency of navigating a potentially dangerous path, since people prefer a nearer path to reach the goal. The theory has been tested in several studies and various navigational costs are associated with distance perception, but many potential costs remain undetermined. The aim of the current research was to examine the perception of lenght of the descent as well as the horizontal surface during day and night, with the assumption that the descent length will be perceived longer compared to its actual distance, and additionally even longer at night. The overestimation of horizontal surface length at nighttime is also assumed. The experiment was conducted in outdoor settings at university campus with 104 participants whose age averaged 23.37 years. Participants overestimated the length of a 4.82-meter-long descent (steep surface) during the day. Nighttime participants additionally overestimated the descent length. A horizontal surface of equal length was overestimated at night as well as during the day, despite the assumption being approximately accurate estimation in daytime. Based on these findings, night is shown to be a potential new condition that affects navigation cost perception. Results are interpreted within the framework of the evolved navigation theory. Contributions of the research are discussed, as well as it’s methodological limitations, due to which it is not recommended to generalize specific results.