The Flame in the Flood

This can be gotten within a few minutes of a new game. Start a game on Survivalist and keep filling your jar with water from the dock and drinking until you have dysentery + a couple other afflictions. Then get on the raft (your health bars won't start ticking down on the island) and paddle outta there. You should die from dehydration just as you reach the first island.

The same technique works if you want to get it later in the game as well, and by then you can also save some Salt to dehydrate even faster.

Notes:
- Dysentery is just one of four afflictions you can gain from polluted water, the other three being Parasites, Listeria and Giardia.
- While sleeping dehydrates, it also cures dysentery. So sleeping to speed up the process won't work.
- You can also use alcohol to dehydrate but it's more finicky since you also have to deal with the "Drunk" affliction which can kill you from exhaustion instead.
- Sashamorning notes that you don't actually have to die to get the achievement, just getting the "dehydrated" affliction is enough. You can cure yourself afterwards if you want