Rainbow Whale Spout
This is a gray whale off the coast of Point Loma, California in February. Within the spout is a well-known optical illusion: a rainbow.
Rainbows can only be seen if water droplets are present with a light source (such as sunlight) that strikes the water at a 42-degree angle. When the light enters the droplets it is refracted, or bent. It is then reflected back out of the droplet, where it is refracted again at multiple angles. This is what makes the color spectrum appear.
Rainbows formed in sea spray, such as this one, are slightly smaller than bows formed from rain or other freshwater sources because saltwater is better at refracting light. However, the difference is so small that it is not noticeable.
Photo Credit: Jim Grant