You are eligible for visa free entry
It needs to be electronically readable and physically intact - not just valid on the date of travel. A passport that's been through the wash, has a torn cover, or has a damaged chip will raise flags at immigration. Keep it in solid condition, not just technically current.
Argentine citizens get an entry stamp on arrival. There's nothing to apply for, no fee to pay, and no approval to wait on before you fly.
Costa Rica legally requires a confirmed ticket out of the country - a flight or international bus booking both work. A one-way ticket with no exit plan will cause problems at the counter, so have something confirmed before you fly.
Immigration has the authority to ask whether you can financially support your stay. The Immigration may ask for proof that you can financially support your stay. Requirements can vary, so travellers should be prepared to show accessible funds if requested. A working bank card with accessible funds is usually enough if the question comes up.
Not always asked, but worth having ready. A hotel booking confirmation or a host's address on your phone is the kind of thing that makes a brief interaction at the counter move faster.
Direct flights are generally limited or unavailable on most schedules, and many travellers connect through Lima, Bogotá, Panama City, or Miami. You'll stop somewhere - Lima, Bogotá, Panama City, and Miami are the usual connecting points. Factor in 12 to 18 hours total, depending on the layover. Copa, LATAM, Avianca, and American Airlines are the carriers most Argentine travellers end up booking with on this route.
The stamp you receive on arrival determines your allowed time in the country, and it can go up to 180 days. The immigration officer sets the exact figure, not a fixed rule. The moment you get your passport back, check the stamp and know your date - don't guess at it later.
A tourist entry doesn't cover either. If your plans involve anything beyond sightseeing and moving around the country, speak to the Costa Rican consulate in Buenos Aires before you travel and get the right category sorted from the start.
If your route to Costa Rica passes through a country on the high-risk list for Yellow Fever, you'll need to show proof of vaccination. This applies based on your travel path, not just your nationality, so check your itinerary against the current list before you go.
Check if you need a visa for your next destination