This phenomenon is caused by a red tide, in which a very large amount of phytoplankton gather, which together form a reddish display during daytime. This is especially strong on sunny days, when these organisms will go to the surface to get as much light as they can. Then, once the sun sets and there is no light, the movement of waves and other animals cause these species to light up in a gorgeous display of luminous blue. Red tides do not always produce this effect, but when they do it is a magical experience.
While it can happen in nearly any ocean, this is a common occurrence in places like Puerto Rico, especially during the months of June to December, when the amount of plankton is at a high.
Though it may be bright to the eye, cameras, especially those with higher apertures, won’t be able to capture the beauty of this phenomenon. While this can be disappointing, I think it makes the experience all the more special, and is definitely something everyone should try to experience once.
