Picture a remote mountain lake so clear you can see every pebble on the bottom. No one sells tickets to gaze at it, yet if a mining company wanted to drain it, people might protest—even those who have never been there. How do we put a number on that feeling in a way that policymakers can use? This chapter explains the economic methods we use to measure nature’s worth, from a weekend fishing trip to the deep satisfaction of knowing a rainforest exists.