The green flash is a natural phenomenon that takes place and has gained legendary popularity on the paradise island of Saipan, Northern Mariana Islands.
How/When can I see it?
It happens at sunset. When the conditions are just right, and the horizon is clear, as the sun is setting, you can see a distinctive green flash/glow right above the top of the sun just as it disappears from view.
Green Flash Video
Here is a clip of Jamaican on Saipan, Walt Goodridge, along with long-time resident Joe Hill catching a glimpse of the Saipan green flash!
Yes, there's even a movie about it!
[from the Saipan Tribune:]
The Japanese movie “Green Flash” filmed on Saipan last Nov. 22-23, 2013. The movie, set to premiere in April 2014, is about three university students working at Karoake Box in Tokyo who travel to the Pacific in search of happiness and the “green flash” natural phenomenon.
Actor Yuya Miyagaki and actress Yui Ishikawa were on Saipan for the shoot. The movie is sponsored by the largest karaoke franchise in Japan, Daiichi Kosho Co., Ltd., and supported by convenience store franchisor Lawson Inc. ...While on Saipan the crew filmed at the Japanese-era lighthouse on Navy Hill, Jonny’s Bar & Grill, Paseo de Marianas pedestrian mall, Saipan Beach Pathway, and Wing Beach. [end of Tribune excerpt]
We can't guarantee that every sunset will produce a green flash, but (1)Saipan IS known for its beautiful sunsets, and (2) even if you don't catch it, you'll have a lot of fun on the island of Saipan chasing the green flash!