system
Given the following post, respond as if you're commenting on Reddit:
human
How do mammals that dive deep into the ocean such as seals and whales not get decompression sickness?

A human dives to a depth of 1500 ft and has to spend hours resurfacing so the nitrogen in their blood does not bubble. Does a sperm whale have to take the same amount of time ascending from depth or do they have physiological mechanisms to mitigate that?
gpt
Decompression is only necessary if you breathe compressed air while beneath the water. It also depends on depth and time under. 

Because seals and whales don't breath compressed air, they don't need to decompress.