What is the independent and dependent variable?

Jeremy is on the planning committee for the rock climbing club. He is putting together a trip where members can go outdoor rock climbing. He is trying to determine how high the group should climb and how long the trip should last. He calls multiple parks in the area that offer rock climbing and collects data on the height of the rock formations and the average time it takes people to reach the top and come back down. The data he found is shown.

Time to Climb (min)
Height (ft)