The Ala Wai Canal is an artificial waterway built in the 1920s that serves to drain several of Oahu's streams and rivers into the Pacific Ocean. More importantly, it stood in for the area of Seoul where Jin and Sun first meet.
In the second season episode ...And Found, shortly after Jin quits his job as doorman at the Seoul Gateway Hotel he walks somberly along a waterway in Seoul. The bridge behind Jin is in reality the bridge that crosses the Ala Wai Canal at Kalakaua Avenue.
The view below is more or less what Jin would see in the screenshot above. He is walking along the "right" side of the Ala Wai Canal.
Jin has been alerted by his buddy that he will soon find love, and that it will be orange. Jin's spirit soars when he spots a lovely young lady in the requisite hue approaching him.
Sadly the lady walks past, but Jin has nary a second of disappointment before he collides with a second beauty, one who will play a very important role in his future...
The Ala Wai Canal shows up again in season 2's follow-up Jin/Sun-centric episode, The Whole Truth. This time Sun walks along the left bank of the canal.
The shot below was taken from the bridge along Kalakaua Avenue towards the ocean. The buildings to the right of Sun in the first screenshot below are those on the left side of the photograph (since the LOST camera is pointing inland).
A canopy of trees lines the right bank of the Ala Wai Canal between Kalakaua Avenue and Ala Moana Boulevard. For me they served as a welcome respite from the scorching hot midday Honolulu sun. For Michael Dawson they set the scene for a sad farewell to little Walt in season 2's Adrift.
Couple more shots from the area ... this one from the right bank, looking out to the left bank, immediately adjacent to Kalakaua Avenue...
...and this one standing on the Kalakaua Ave. bridge looking down the left bank towards the ocean.