The sea otter is an endangered marine mammal that plays a vital role in maintaining healthy coastal ecosystems. Sea otter populations have declined due to historical fur hunting, oil spills, pollution, disease, entanglement in fishing gear, and habitat degradation. As a keystone species, sea otters help control sea urchin populations, allowing kelp forests to thrive and support countless other marine organisms. Protecting sea otters and their habitat is essential for preserving the biodiversity and balance of coastal marine ecosystems.