There's poison ivy in Algonquin Park, but it's usually avoidable.  This is the first time I've really had no choice but to walk through patches of it.  I have a fairly strong reaction to poison ivy, so I figured I'd post a warning for others so they can be prepared.

The first 'trouble' poison ivy was on the 2110m between Upper Spectacle and Little Carcajou.  I think if you take the 300m pond detour to skip the middle section of the portage, not only would you skip the majority of the poison ivy, but you also skip the most difficult section of the portage.  I was able to carefully walk around the poison ivy here, but it just required some extra maneuvering as it was overhanging the trail.  The detour is actually well marked with portage signs, though the Southern-most sign is facing away from the pond, but the tree is marked with orange/red ribbon.

I was originally supposed to stay on the site on Little Carcajou, but changed to Carcajou when I picked up my permit.  I did stop for lunch at the site on Little Carcajou to check it out, and there was poison ivy on the trail to the thunderbox.

The poison ivy got progressively worse heading through Carcajou towards the power line.  On the 285m leaving Carcajou you basically have no choice but to walk through the poison ivy.  It's unavoidable.

The 535m to the power line didn't seem to have a poison ivy problem.  I also didn't see any on the 5070m back to Grand Lake, but that trail is wider so it would be easier to avoid any patches.

If you're going this way, you're definitely going to want to wear pants and closed shoes.  Probably also a good idea to wash off sooner rater than later.