Set up a rope/string trail between trees. Attach a mug to the rope by threading it through the handle. If need be, attach others along route where string is tied to trees etc.
Scouts have to fill mug with water and travel blindfolded along trail, without spilling a drop. They may need to transfer water to other mugs as they reach them.
rope / twine (lots), mug/s, water, other items as appropriate in order to confuse etc.