Things to see
Much of Colombia is in the Andes, which means there is very beautiful mountainous scenery to be found. On the other hand, there are also nice beaches to be found in the lowlands. The altitude of some peaks mean that snow can be seen even though they lie in the tropics.
Things to do
There are a lot of things to do in Colombia, and you can find parties and celebrations wherever you go. Colombians especially love to dance, and if you don't know how, they'll happily teach you. Colombia is known for its exciting night life.
There are many groups and agencies offering eco-tourism and it is very usual to find trekking plans (locally named 'caminatas' or 'excursiones') on weekend; many groups (named 'caminantes') offers cheaper one day excursion, special trips (on long weekends or during periods of vacation time (January, Holy Week, July, August, October, December) to different places in the country. Some recommended groups based out of Bogotá are: Viajar y Vivir, Fundación Sal Si Puedes, Caminantes del Retorno; there are many other. Patianchos in Medellín; Rastros in Bucaramanga. They usually offer guidance and transportation to the place; on long trips include lodging and other services. The recommendation is asking if the guide has the official certification.