If you like beautiful nature, I recommend you go to Seongsan Ilchulbong or Samyang Black Sand beach. Also, most tourists do tangerine picking experience because Jeju Island is famous for tangerine. However, It's better not to go to famous restaurants or cafes. They demand a high price food or coffee. I hope you find place that people don’t go much.

Oh this is lovely Sarah! How I wish I'm one of this many Chinese to lived Jeju Island, kidding. Here's a revised version of your answer. T Linda

If you like beautiful nature, I recommend you go to Seongsan Ilchulbong or Samyang Black Sand beach. Also, most tourists do tangerine picking experience because Jeju Island is famous for tangerine. However, It's better not to go to famous restaurants or cafes. They demand a high price food or coffee. I hope you find place that people don’t go much.