Olaus Magnus (1490–1557), archbishop of Uppsala from 1544, created a 1539 map, the Carta marina, and wrote two map explanatory keys and a 1555 text, Description of the Northern Peoples. All featured depictions and discussions of sea monsters in the water surrounding northern Europe. Analyzing these works, this article argues that Olaus conceptualized both sea monsters and the water that contained them as wonders or marvels. It extends the insights of modern scholarship on wonder and wonders to the topic of water. In doing so, it also claims that these findings suggest that scholars should analyze sixteenth-century European conceptions of water more broadly. If Olaus's contemporaries viewed the water through which they traveled as a wonder, then this conception of water could have drawn Europeans to investigate and dominate the Atlantic, Pacific, and Indian Oceans, even as they wondered at the locations, objects, animals, and peoples to which they led.