Why is the deep ocean cold and dark?

WHY THEY ARE DEEP>>>>

according to: amnh.com

the oceans are deep because it states that  "The ocean is very, very deep; light can only penetrate so far below the surface of the ocean. As the light energy travels through the water, the molecules in the water scatter and absorb it. At great depths, light is so scattered that there is nothing left to detect."

WHY THEY ARE COLD>>>

according to: ocean service.com

oceans are cold because it states that  "Cold water has a higher density than warm water. Water gets colder with depth because cold, salty ocean water sinks to the bottom of the ocean basins below the less dense warmer water near the surface"

WHY THEY ARE DARK>>>

according to amnh.com

Oceans are dark because it states that "The ocean is very, very deep; light can only penetrate so far below the surface of the ocean. As the light energy travels through the water, the molecules in the water scatter and absorb it."

pythagoras' theorem

square root (-5^2+9^2)

square root (25+81)

square root (106)

angle is tan^-1(9/5)

neg x, pos y