Net pens are large, floating enclosures used in aquaculture to raise fish in open water. These structures are typically made of nets and are anchored to the seabed, allowing water to flow freely through them. This design helps maintain a healthy environment for the fish while preventing them from escaping into the wild. Net pens are commonly used for farming species like salmon and trout. They provide a controlled space for fish to grow, making it easier for farmers to manage feeding, health, and harvesting. This method of fish farming is popular due to its efficiency and relatively low environmental impact compared to other methods.