hammock and trees
A hammock can easily been hung between two trees. Or between a tree and a wall.
However, be aware that a tree just beneath the bark transports its food .
A tight rope can obstruct this stream and thus squeezing a tree to death!
Make sure you use a strap (for sale at do it yourself shops), instead of plain rope, so that the tree is protected.
At Accessories see "Tree Huggers". These can be bought with a hammock and "hug" the tree.