Why couldn't explorers use landmarks to guide them?

Explorers often faced challenges in using landmarks for navigation due to factors like changing landscapes, poor visibility, and the vastness of uncharted territories, which made recognizable features scarce. Additionally, many landmarks could be misleading, as they might not be visible from a distance or could be obscured by weather conditions. Furthermore, explorers ventured into areas where they had little prior knowledge, making familiar landmarks nonexistent. As a result, they relied more on navigational tools and celestial navigation rather than solely on landmarks.