Backyard Zip Line
Many people have set up a backyard zip line. It's not difficult to do in short distances such as a backyard and kids really love it. Ziplines for backyard space can be created with relatively low height. Some platforms are the swing set, tree house, or playground equipment.
Zip line kits offer an easy way to put up a zip line in your backyard at a reasonable price. Short, ready-to-install zip lines are perfect for the backyard or a nearby field, even a playground. They range from about 35 feet in length to 90 feet, and can be installed from tree to tree without the need for a lot of drop in elevation. The sag in the cable provides a nice drop down to the low point, slowing or stopping just short of the end. To make the zip line run a little faster tighten the cable and add just a little drop in elevation. It isn't necessary to install short zip lines on a hill. Flat backyard spaces work quite well. You can achieve a couple foot drop in elevation from start to finish simply by anchoring the end a little lower on the tree.
These kits are designed with families and backyard-sized areas in mind. They can be set up in a few hours. Some kits can even be set up with only one person, but most require two. The tensioning can be done without a cable puller, but many reviews recommend the small additional expense of a Zipline Cable Winch. This tool will make installation of your zip line much easier. Several comments about ziplines of this size mention the sag in the middle. This can be resolved with the cable puller winch, so it's a good idea to add it and save the effort of re-tensioning the cable.
Another thing to consider is getting a tree protector kit. Protect the trees in your backyard from the zipline end cable. Most kits don't include tree protection, and the end anchor wraps around a tree or pole. This will damage the tree with extended use. It's perfectly fine to use a sturdy tree for both starting and ending points if some type of protection to the bark can be done.