No1 - Get the country name right - its Colombia; it is also pronounced with the o as in dog. From my experience many Colombians get titchy when Gringos pronounce their country Coloombia as the North Americans have a tendency to do.
Anyway, my wife is Colombian and suggests the safest way is by air. If you go by land, which is difficult given that it is mostly jungle, when you hit Northern reaches of Colombian you are in one of the areas where guerillas are likely to operate.
Wishing you a safe and enjoyable trip. Colombia has many fantastic features that the world doesn't know about or chooses not to know about. The country is like most others; be aware and take safe options and you shouldn't find your self in an awkward situation. almost 10 years ago