Geocaching
If you have a GPS device this outdoor activity can be fun for the entire family. A geocache is usually a weatherproof box in a specific geographic location. It can hold objects meant to be taken by those who find it, or in some cases may contain objects that are left by those who have visited the site. It is kind of like a treasure hunt, and there are hundreds of places all over the world that you can hunt for. You can look up lists of geocache locations on the Internet and find some close to your home, then you use your GPS device to find the location. Geocaching sites include Geocaching.com, Navicache.com and TerraCaching.com.
A simpler version of this activity is to use a compass and items you hide in your backyard or a park. Lay out a map or instructions, then have your family use the compass to help with direction. This is called orienteering.
Outdoor Cooking
Try cooking a meal outside--not with a grill, but with a campfire. Money spent won't be any more than you normally would spend for a meal, and you can either use a fire pit that you already have or create a fire ring. Make everything for your dinner on the fire. This will take planning by all to make sure that everything is finished cooking at about the same time. Things like vegetables can be wrapped in foil and placed in the hot coals along the edge of the fire.
Stargazing
Look at the stars. Some quick research on one of the Internet sites listed in the Resources section will aid you in finding stars and constellations in your part of the world. If you happen to have a telescope, then try looking up close at some of the stars and planets. The kids will enjoy having a little time figuring the stars out with their parents, and all will benefit from the fresh air.
Clean Up
Volunteer for a cleanup project at a river, lake or roadside. This is a good way to show your kids that it is important that we each do our part to keep the world in top condition. It will also make them think twice about throwing trash on the ground themselves. Other benefits are the exercise and time spent as a family.
Harvest
Go to a local farm to pick some produce. In addition to the outdoor air, exercise and family time, this activity offers a learning experience for kids. They get to see how certain types of foods are grown and picked. They will see what these foods look like when they haven't fully grown or aren't ripe and what they look like when they are, learning a lesson in the life cycle of plants.