I just found one on both sides of coastline. One side had a very very long one. I tried to stay a good distance away, but they were on both sides and it was narrow. It was ocean (not the deep dangerous kind) but it narrowed into not much wider than a river.

It wasn't night but close twilight. Knew not to be there with a boat but no where to land. Had been in rain and high seas for over a day. Saw 2 leeches and heard a sort of thump.

Cleared the swamp and cam to meadow, thank Odin. Left the boat in swim depth but close enough to get to. That minimizes greywolves and boars started to hack at it. Went to work on a base there far enough from swamp not to draw those mobs in.... getting off track. Long story short, worked on cabin all night, never heard anything but boat was gone in the morning.

Think that 1 leech maybe latched on and ate it, lol. Just my cargo of copper ore was floating in a box. Amazing that copper floats like that.