Sea foam, the frothy, bubbly substance often seen tumbling onto beaches, is a common natural phenomenon created by the agitation of seawater. While usually benign, certain environmental conditions can transform this ocean froth into a significant hazard, particularly for surfers immersed in the water for extended periods. The danger arises because the foam acts as a concentrating mechanism, collecting various biological and chemical materials. Understanding the underlying science of foam formation is the first step in recognizing this potential threat.
The Science of Sea Foam Formation
Sea foam is formed when dissolved organic matter (DOM) in the ocean, such as proteins, lipids, and decaying algae, is vigorously churned by wind and waves. These organic compounds act as natural surfactants, or foaming agents, which reduce the surface tension of the water. When the ocean is agitated, these surfactants stabilize air bubbles, allowing them to persist and cluster together instead of bursting.
This foaming process works as a natural filter, concentrating substances present in the water into the dense bubble matrix. The surface microlayer of the ocean, the very top film of water, harbors pollutants and microorganisms that are captured within the foam structure. The concentration of contaminants in the sea foam can be tens to thousands of times higher than in the surrounding seawater. Thick, persistent foam is a visual indicator that high levels of these materials have been collected from the water column.
Health Risks from Biological and Chemical Contaminants
A primary health concern comes from the concentration of biological pathogens, particularly after heavy rainfall or near urban runoff. Storm drains and sewage outflows carry bacteria and viruses into coastal waters, which the foam efficiently traps. Exposure to foam containing pathogens can lead to gastrointestinal illnesses, skin rashes, and ear or eye infections in surfers. Studies have identified specific harmful bacteria, such as Nocardiae, concentrated in sea foam, which cause infections, especially in individuals with weakened immune systems.
Chemical toxins also accumulate within the foam matrix. Harmful Algal Blooms (HABs), often called Red Tides, produce potent toxins that are readily concentrated and aerosolized by the breaking foam. When surfers wipe out or duck-dive, they risk inhaling these airborne toxins, which can cause respiratory irritation, coughing, and the exacerbation of asthma. Synthetic contaminants, like per- and polyfluoroalkyl substances (PFAS), also known as “forever chemicals,” are highly concentrated in sea foam. Ingesting foam laced with these chemicals, which is common during a turbulent wipeout, exposes surfers to substances linked to long-term health issues affecting the liver, kidneys, and immune system.
Immediate Physical Dangers
Beyond invisible contaminants, the physical presence of dense sea foam poses immediate mechanical risks to surfers. Thick banks of foam severely reduce visibility, making it difficult to spot incoming waves, submerged rocks, or other surfers. This loss of visual awareness increases the risk of collision or being caught inside by a large set.
The foam also creates a slip hazard on the sand and rocks when entering or exiting the water, making secure footing challenging. When covering the surfboard, the slick foam reduces traction, complicating paddling or standing up on a wave. Inhaling large volumes of the physical foam mass during a wipeout can lead to temporary breathing difficulties and disorientation.
Safety Guidelines for Surfing in Foamy Conditions
Surfers should exercise caution and avoid the water when sea foam displays unusual characteristics. Stay out of the ocean immediately after heavy rainfall, which commonly triggers sewage and pathogen runoff into the surf zone. Avoid surfing if the foam appears discolored (such as reddish-brown or yellowish) or if it has a foul odor. These characteristics are indicators of a toxic algal bloom or heavy pollution.
After any surf session in foamy water, thoroughly rinse off with clean, fresh water immediately. Pay close attention to washing the eyes, nose, and mouth to remove any concentrated contaminants that may have been inhaled or swallowed. If you experience persistent respiratory distress, severe gastrointestinal issues, or skin rashes following exposure, seek prompt medical attention.