The salt ponds of San Francisco Bay give off incredible purple hues. What you are seeing is not photoshop or manipulated in any way at all, it is actually billions of microorganisms living in the shallow salt ponds. Photographer Julieanne Kost has managed to capture these salt ponds in all their glory.
It takes around five years for the bay water to be completely transformed into salt brine, and during that time various organisms live in the ponds. You can learn more about the process here.