After travelling to Ipiales from Pasto and stopping for the morning to visit the Las Lajas Sanctuary we undertook the border crossing to Ecuador.
The easiest way to get to the border is by taxi from the bus terminal for 7,000 pesos, an alternative is a collectivo for 2,000 pesos per person, from the same place. The actual border crossing is located only a 10 minutes drive away.
Ask the driver to drop you off at the Colombian border side for your stamp out as otherwise they will take you across the bridge to the Ecuadorian border. The process is very simple, there are no exit fees to pay and you are simply stamped out.
Once you have your stamp walk across the bridge to the Ecuadorian side, a 2 minute walk, and head into the building on the right. Again there are no fees to pay for entry but you do need to fill in an immigration form before you queue for your stamp.
To carry on with your travels, once stamped into the country, walk across the road and take a collectivo to Tulcan, the first town in Ecuador. The half an hour ride should cost you around a dollar each. Note that in Ecuador the local currency in US dollars.