Originally posted by Mharr:

Don't make landfall in the swamp, set up a forward base in a safer location near its border and link up a portal. If there's no better biome nearby build a small sea fort starting from a partly submerged rock or tree.

100% this. Find a nearby biome that's safer than the swamp (mistlands, meadows or black forest), toss up a workbench and a portal back to your main base in case you die again, and make a run for it.

If you can't seem to make it, ask some of the helpful Vikings here on the forums for help! I'd be more than happy to run protection for you and I'm sure others would as well. Good luck!