IBM’s crewless AI-powered ship is due to begin roaming the oceans this month, collecting vital data about something we still know incredibly little about.

Humans have travelled the sea in some form for tens of thousands of years—with the earliest crossings occurring around 53,000 to 65,000 years ago (when Australo-Melanesian populations migrated into the Sahul landmass – known today as Australia and New Guinea – from what used to be the Sundaland...