Entering Colombia either by plane, bus or boat is straightforward for most travelers.
You'll need a valid passport (with at least six more months of validity) and some nationalities will need a visa. Travelers receive a 90-day tourist visa, which can be extended for another 90 days per calendar year.
Nationals of many countries, including those from Western Europe and the Americas, Japan, Australia, New Zealand and South Africa, don't need a visa. Otherwise, expect a nominal fee.
Canadian travelers do not need a visa but will be charged a Colombian equivalent of C$85 reciprocity fee upon arrival at the airport or land border crossing. It can be paid in cash in Colombian pesos or with an international debit or credit card. It is waived for travelers under 14 or over 79. At international airports there is a special immigration line to pay the fee, marked with a Canadian flag.
All visitors get an entry stamp in their passport upon arrival and receive a 90-day tourist visa. Double-check your stamp immediately; errors are sometimes made.
If traveling overland, make sure you get an entry stamp or you'll have troubles later. Overstaying your welcome can result in heavy fines, and in some cases can result in being barred entry in the future. Similarly, make sure you get your departure stamp or there will be trouble the next time around.
Migración Colombia handles visa extensions for tourists via Centros Facilitadores de Servicios Migratorios offices around the country. Visitors on a tourist visa may extend up to an additional 90 days at the discretion of the officer. To apply for an extension, known as a 'permiso temporal de permanencia,' you'll be asked to submit your passport, two photocopies of your passport (picture page and arrival stamp) and two passport-sized photos, along with an air ticket out of the country in most cases. The fee of COP$96,000 can be paid by debit or credit card at Migración Colombia offices.
If you're paying in cash it must be deposited into the government bank account, which is often Banco de Occidente but depends on the city in which you are applying. Show up first to fill out forms, then they'll direct you to a nearby bank to pay the fee.
You can also complete the process and pay online and once it's approved pop into a Migración Colombia office to get the stamp.
If you apply for the extension in the office, expect the process to take an entire morning or afternoon. It can be done at any of the Centros Facilitadores de Servicios Migratorios offices in Colombia, which are present in all the main cities and some smaller towns (there's a list on the Migración Colombia website). You'll usually (but not always) get the extension on the spot.
Fines for overstaying range from half of to up to seven times the minimum salary (depending on the length of overstay): travelers in 2018 were charged at least COP$450,000 for overstaying a few days.