Line in the Sand is a new quest in Arc Raiders' Riven Tides update, though it's got nothing to do with the new seaside paradise. This actually continues the story of Stella Montis and Buried City, where Exodus materials were being transported.
You'll need to find four locations across Buried City to complete Line in the Sand, and they're not the easiest to pin down. I'll show you where you need to go below for the mission so it won't take you quite as long as it did for me.
Find out why the train never reached Marano Station
Embark
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