Navigation ability varies widely across humans. Prior studies have reported that being younger and a male has an advantage for navigation ability. However, these studies have generally involved small numbers of participants from a handful of western countries. Here, we review findings from our project Sea Hero Quest, which used a video game for mobile and tablet devices to test 3.9 million people on their navigation ability, sampling across every nation-state and from 18 to 99 years of age. Results revealed that the task has good ecological validity and across all countries sufficiently sampled (N = 57), age is linked to a near-linear decline in navigation ability from the early 20s. All countries showed Results from project Sea Hero Quest are reviewed, in which 3.9 million people across 63 countries took part in an online app-based virtual assessment of navigation skill. Key findings to date are: a) navigation skill declines linearly across the adult life span, b) a male advantage partially predicted by metrics of gender inequality across countries, c) navigation skill is geographically clustered across our planet, with Nordic people, north Americans and antipodeans performing best across countries sampled and d) growing up in cities with grid-like layout has an overall negative impact on navigation skill.