If you are not accustomed to hiking in the Northwest Climate zone you may not be familiar with a few nasty plants we have here. On several hikes in this area I saw stinging nettles and devils club lining the trails.
These plants certainly will not kill you but they are not pleasant. Stinging Nettles are similar to a bee sting when touching any part of the plant. Leaves, stem, stalk anything. If you do accidentally encounter stinging nettles the best remedy is to use an antihistamine and avoid itching.
The devils club is quite different. It has very hardy thorns which are far more destructive than your average blackberries or sticker bushes. Best to simply avoid these or find some nasty scratches and maybe a few slivers.
While the falls are beautiful one needs to be careful while hiking to the top. The trails are often narrow and damp. I have seen people in ahurry hit a slippry spot and lose thier balance. This can be fatal if you are at a narrow and high spot. Even the area I am standing in at the base gets wet and slippery at certain times of the year.