Branden Rishelcreated this map showing only the world's time zones — without any of the land underneath. It highlights just how unusual these artificial boundaries can be:
Time zones were meant to solve the problem of different solar times around the world (solar times are what time it feels like based on the sun's position in the sky). The idea for a worldwide time-zone system gained currency at the International Meridian Conference in 1884. By the 1900s, the idea was widely accepted and practiced.
Still, that idea has led to some quirks that are visible in the map above:
That huge jag in the top left corner is the adjustment for Alaska, which is one single time zone. Politically, it makes sense that Alaska time would be the same everywhere, but in practice it can be confusing, since the solar time can vary two to three hours from the clock time.
Moving to the center, you can see the outline of Argentina, because it uses the same time zone as eastern Brazil (unlike Bolivia and Paraguay, which sit above Argentina and use the time zone used in western Brazil).
India is visible because despite its size, the entire nation has adopted Indian Standard Time since gaining independence from Britain. That has, however, caused some states to protest and follow their own time zones.
China spans what would normally be five hours of solar time — but you can see its outline on the map because it only uses one time zone. Though this has occasionally caused difficulties in Western provinces, the country officially lives on "Beijing Time."
For comparison, here's a time zone map with the countries shown:
Irregularities like those are part of the reason some make the argument we should move to a single Earth time instead of many time zones. But for now, you'll have to stare at the time zones' contortions.
/cdn0.vox-cdn.com/uploads/chorus_asset/file/3552532/800px-World_Time_Zones_Map.0.png)