Acoustic echoing (sonar) or satellite scanning methods.
pacific
add together the depths and divide the sum of the depths by the number of times you have measured the depth
no
In the ocean, sometimes at great depths
They live in various depths in the ocean
in the depths of the ocean
They live in various depths in the ocean
The major environmental factor limiting the numbers of autotrophs at great depths in the ocean is the amount of light reaching those depths
The deepest parts of oceans are dark all the time because natural light does not penetrate to the ocean depths. Little is known about life in the depths of the ocean. More is known about the moon than the depths of the oceans. Water pressure is great, the temperature is constant.
IN PONDS AND SWAMPS
Jacques Cousteau
Blubber