Originally posted by Grailoch:

If you don't have any swamps within walking distance you will want to make a Karve before heading towards swamps. Just don't leave it at the shore. Break it down and store it in a chest until you need it again. I just lost my first Karve and have had to get materials to replace it. Thought it would be safe where I left it, but something must have seen it while I was exploring the area.

Ships also like to just randomly die. I've stood there and watched a longship capsize in a calm bay and damage itself until it died. There we no enemies around.