Near Barcelona, foamy sea foam covered different streets in the small town of Tossa de March.
Algal blooms refer to a quick accumulation of algae in freshwater or marine water systems and are one of the most common sources of thick seafoam.
Divers from the Guardia Civil are searching the sea near where he disappeared. Sea foam then forms as that organic matter is churned up by the surf, according to NOAA.
Storm Gloria has left 200,000 people in the country without electricity, has closed down schools and blocked roads since Tuesday morning. Local residents were seen assisting in removing the foam but a constant wind kept whipping it up, hampering clean-up efforts.
Spain's Prime Minister Pedro Sanchez has announced an emergency meeting to deal with the impact of Storm Gloria after flying over areas of eastern Spain where heavy rains, powerful winds and huge waves have killed at least 11 people.
Officials in Barcelona said the city's beaches had lost a lot of sand due to the high, strong surf.
Several people, including one British ex-pat, took advantage of the unexpected freebie and headed to the seafront with large knives to cut off the best steaks.
On Wednesday, the body of a man was recovered in a flooded area near the town of Callosa, in southeastern Spain. Some areas saw their heaviest rainfall in more than 70 years.
The most affected regions include northeastern Catalonia, where authorities still monitored several rivers on Thursday for fear of overflow, and southern Andalusia, parts of which were hit by a sudden hailstorm early Thursday.