The Cartographer's Lie

You get a hex chart of an island and a few notes from the surveyor. Every note is true. One hex is drawn as something it is not, and exactly one hex satisfies all of them at once. You have three corrections to find it. Because every note is true, you are never guessing, you are eliminating. On one chart the notes read: south of every trig point; falls on Sheet III; touches exactly 0 reefs; drawn on reef or heath. Every reef on that board sat beside another reef, so the third note wiped the entire reef terrain, and the fourth then forced heath. Four flat statements collapsing onto one hex. A new chart goes up daily at 5am New York time, and a solve takes about three minutes. There are four difficulty tiers and the browser opens on the gentlest one. Streaks and a career record carry across days. Free in the browser with no account and no signup. There is an iOS app as well, but you do not need it; the web version is the full daily puzzle.