Nature's Playground is an amazing book by Fiona Danks and Jo Schofield that will inspire your family with all kinds of outdoor adventures.
The book is divided into seven sections: "Let's Get Outdoors" is filled with basic getting started tips. Four seasonal sections are filled with all kinds of wonderful things to build with natural materials from that season from twig sculptures in "Spring" to elf houses in "Autumn" to ice mobiles in "Winter". "All Year Round" describes activities you can do any time like tree climbing, scavenger hunts, and wild dens. "After Dark" describes nighttime adventures and crafts.
The book is a feast for the eyes with beautiful photography throughout. Even my non-reading children love to pour over the pages to get ideas of things to do. For those who want or need more inspiration, the text describes where to go and what to bring and how to get started for each of the pictured activities.
If you are looking for some inspiration to enliven outdoor walks with your children, this is my favorite of the nature activity books out there!