Eels are long, snake-like fish that live in both freshwater and saltwater. They have smooth, slimy skin and can be found in rivers, lakes, and oceans around the world. Eels are known for their unique ability to swim backward and can often be seen hiding in crevices or burrowing into the mud. One of the most fascinating types of eel is the European eel, which migrates thousands of miles from rivers in Europe to the Sargasso Sea to spawn. Eels are also popular in various cuisines, especially in dishes like unagi, a Japanese delicacy made from grilled eel.