There are many videos about the routes of Jeju Olle Trail available on YouTube. Many of those videos have Korean language titles and are therefore difficult to find for non-Korean speakers. This is a problem because they are the most up-to-date and best quality videos.
Jeju Olle is 제주올레 in Korean. The Korean word for route is 코스. Knowing this now makes a search much easier. Simply copy and paste 제울레 1코스 into the YouTube search box. Then check the thumbnails for relevant results. Of course just switch the 1 with another route number and you’ll be able to go through all. Refine results using the site filters. Enable subtitles and auto-translate to English for a gist of the accompanying commentary.
There is one thing to consider about watching videos on YouTube. Some slickly produced top quality 4K drone footage is not a true representative of the route and may not be exactly what a walker will experience. Especially on a windy rainy day with poor weather. So please take each wonderful artistically edited video with a large grain of realistic salt.
Below is a pre-selected video for each route. Right click to open in a new tab.
Jeju Olle Trail Official English Guide 