leaving everything in its place is mandatory -  building any kind of structure, such as benches, tables, bridges  is not allowed.

breaking or cutting tree branches, even if they are dead or fallen, is not permitted as they may be serving as shelter for birds or other animals.

it is important to resist the temptation to take 'souvenirs' home - rocks, artifacts, flowers, shells etc. should be left where they were found, so that others can also enjoy them.

the saying is true - it is important to take only photographs, leave only light footprints, and  only  bring home memories.