Caño Cristales (Colombia) The river appears in many hues–including yellow, green, blue, black, and especially red–which are caused by the Macarenia clavigera (Podostemaceae) at the bottom of the river.
Santa Marta, Colombia -- La Ciudad Perdida (The Lost City). Hidden (literally) in the crevices of northern Colombia’s Santa Marta Sierra Nevada mountain range, La Ciudad Perdida was built by the Tayrona people around 800 AD.
Beautiful colonial streets of Cartagena de Indias, Colombia - This would be a beautiful place to visit. Interesting food and genuinely nice natives, but there is always a sense of insecurity in a developing nation.