Cheap KLM flights San José (SJO) to Ulsan (USN)

Use the "Price (lowest to highest)" filter on Expedia to find cheap KLM return flights from SJO to USN. Affordable one-way options are available too.**These prices were available on Expedia within the past 7 days, for flights departing within the next year. Prices and availability are subject to change. Additional terms apply.

Start your search for KLM flights from SJO to USN about one month before you want to leave. The most affordable time to book an international flight is usually 18 to 29 days ahead of your departure date when you can save 17% versus booking four to five months in advance. No matter your itinerary or fare class, the best day to book international airfare is usually Sunday. Friday can be the most expensive. Passengers booking on a Sunday can save 17% on average compared to those who book on a Friday.**Ideal booking window recommendation is based on average round-trip ticket prices for January through November for 2024. Best day of the week to book recommendation is based on average round-trip ticket prices for January through October 2024. All data sourced from ARC's global airline sales database.

Sort your results by "Early Morning" and "Morning" to browse the earliest flights from SJO to USN. Jetting off early means you're less likely to experience cancellations.**Most reliable time of the day recommendation is based on January through August 2024 flight status data sourced from OAG's global flight data platform.

A 4-star airline rating and the chance to rack up points through KLM Flying Blue are the start of the reasons to jet off from SJO to USN with KLM. Plus, when you sign up to our One Key™ program, you can earn OneKeyCash™* in addition to any airline loyalty program earnings. It's yours to spend on future travel plans.*OneKeyCash™ disclaimer - OneKeyCash™ is not redeemable for cash and can only be used on Expedia, Hotels.com and Vrbo.