Radar
A handheld tool, labeled "Radar" in-game, that displays nearby points of interest as dots on a green grid.
Directly labeled on-screen in the official gameplay trailer. What the detected dots represent (fish, loot, players) is not confirmed; only that the tool exists and is called "Radar." A gameplay video refers to this as "boat radar," suggesting it may be a boat-mounted system the player views on a handheld screen, rather than a separate portable device. Not confirmed against the trailer footage, which only shows the handheld device itself.