Climb a tree is an int./adv. exercise that works the whole body (of course), and especially focuses on the abs, back and hamstrings. Learn Climb a Tree
You can try this exercise on the mat, but I'm showing climb a tree here in its fully glory on the Pilates reformer. If you don't have a reformer, you will still learn a lot by seeing the exercise. You might also want to try some of the mat exercises that help with climb a tree skills such as knee folds (fundamental) roll up, and teaser.
image (c)2011, Marguerite Ogle