A lovely (and less-trodden) trail that takes up up to Las Cárcavas. A really stunning walk - not too strenuous, that you are likely to have all to yourself. Be sure to bring water!
Man-made blue pools of water in the arid land not far from Villa de Leyva. Doable by foot from town, and you can explore the pools via a short (and well-marked) walk.