Biofouling

Biofouling is life attaching itself to a hull. The reason this is considered undesirable is that hulls are designed to be smooth for efficient movement through the water, and any change in the friction coefficient of the hull is generally to the detriment of fuel efficiency and speed. Another problem with living things attaching themselves to the hull is that they compromise the anti-corrosion measures taken to protect steel hulls and metals inside the hull, or may weaken wooden or composite hulls' structural members.

Bio-fouling may be plant life or sessile marine animals, such as coral, barnacles, or even shellfish.

Certain materials and designs may be less vulnerable to accumulation of biological growth, particularly concrete floats. This may even form a strategy for Aquaculture. In cases where this is desirable, a better term would be "bio-accumulation" to indicate the positive aspect in this context.