Once you pass 1,000 meters, the water is completely devoid of light, and you have reached the deep ocean. Down here, temperatures plummet to 39 degrees Fahrenheit, and constantly stay near freezing. The pressures at these depths range from about 40 to over 110 times the pressure of Earth's atmosphere. We know more about outer space than the ocean floor. Want to learn more about the ocean? Start with this mind-blowing series! , narrated by ... David Attenborough

• David Attenborough