find crypts, small stone buildings with two torches and an iron gate, that's where all the scrap iron is. Jump on top and place a travel portal to base. use that portal to return home when need to repair, drop off non-ore/ingot stuff, and rest. run the scrap back to your boat. once done with a crypt tear down the portal and move to the next one. once boat is full, take it all home.
You should be using a mace in the swamp. Most things are resistant to piercing damage, but all things in the swamp take normal damage or are weak to bashing, this includes the boss.
Take things slow since stamina and health recovery is constantly thwarted by being wet.