Your task is to find the small container nearby and sign the "log". It is not a raft nor made of wood although that "wood" have been clever. Beware "runners" on foot that might wonder what you are doing. Or introduce them to our game. Bicyclists may also be curious. Bicycles were invented and refined during the time the river runners were active.
Note that the ivy near the container is NOT poison ivy. I'm an experienced scout leader. The tree with the cache has English Ivy. I added a picture to the gallery. The tree next to it has poison ivy vines (not leaves now); I added a picture of those vines as well.
Congratulations to MidnightsRaiders and GableGang on the First-To-Find.