Large masses of sea foam on Salmon Creek Beach, 23 December 2014. Some of the foam was knee-high.
The winter lighting and low tide conditions sometimes made this seascape look like "icebergs."
With a light breeze off the ocean, the foam sailed across the surface towards the beach. Look for the trails of bubbles left behind by the foam patches (below).
A close-up of a sea foam cloud:
Sea foam can be associated with high concentrations of diatoms, phytoplankton cells, seaweed mucilage, proteins or lipids. Its formation also requires a source of gas bubbles, e.g., via mechanical agitation such as large waves.
Facts above from Schilling and Zessner. 2011. Foam in the aquatic environment. Water Research 45: 4355-4366.