I mentioned this in another thread, but each Biome is designed to teach (And punish you for not learning) certain mechanics.

The Swamp is all about Debuffs and buffs. The swamp is an absolute nightmare for the unpepared, you will need Poison resist meads, and you will need to get very accustomed to maintaining 100% uptime on the "Rested" buff. In the swamp, you have no access yet (At least in normal progression) to a warm cloak (Wolf, Lox or Feather) so night is especially brutal. The constant wet debuff and the cold debuff mean stamina regeneration is almost completely nullified.

Always keep materials to make a fire on you (2 wood, 5 stone, you can retrive the stone) but also learn where you can and can't make fires, and where you can rest. It may seem like with the constant rain you can only rest inside Crypts (And this is a valid strategy) but basically any object that occludes the sky will protect your fire and yourself from the rain. So plop a fire under a log ( With enough room for the fire to breath) and squat next to it for 30 seconds. Get your rested buff, and move on.

To a lesser extent, the biome also teaches you about weapon resistances and weaknesses. A mace will save you a lot of grief in the swamp, as most of the enemies are weak to blunt.