The seafloor is more than just the ground beneath the sea. Two-thirds of Earth's surface is covered by oceans, which have an average depth of almost 4 kilometers (2.5 miles). For a long time, the seafloor's remoteness protected it from widespread human disturbance. But that is changing: Bottom trawl ing now reaches depths of around 4,000 meters (13,100 feet) and already disturbs up to 2% of the global seafloor each year. ...read more read less