Definitely swimming - it's by far the easier option, I tried to kill off a virtually no-stat alt at the end of last world via death by boar, it just flatly refused to kill me, after spending ages running in and out of it's radius trying to make it even attack, it just knocked me out and wandered off.
I had to wander around playing on the char just to get enough lp to buy swimming - in hindsight I'm not sure why I even went to all that trouble, frustration I guess, just don't log onto it, lol.
One thing though, later on in the game you may be glad of an alt or two, if you are playing alone you will need two chars at some point, one for industry/mining and one for nature/farming. When it comes to building walls you will need a key alt to keep your gate keys safe until you are able to build b/walls and xrd's. Also, I like to have a sort of combo back up alt in case of death which can then be made into whichever char you've lost.
Alts are also extremely handy for dropping pclaims onto cave entrances or for securing any nodes you may want to keep to yourself.
So, don't be too hasty to kill him off, you may need him in the future, just log onto it now and again and feed excess or low tier curios, it soon adds up.
