Use deer god buff when running too and from your boat, don't stop for anything and I assure you enemies won't catch you. Having good stamina food should be a given anyway, what with all the mining you'll be doing in the crypts.

All your time in a swamp should be spent in a crypt with as little time as possible running to and from your boat to load up with scrap iron. Once you have full Iron gear, THEN consider hunting the swamps surface for materials.