We have never been able to see a live birth among the great whales. But it does seem reasonable that pregnant whales would want to find sheltered, quieter waters to birth. Baby whales also have a much thinner blubber layer, so warmer water may be important for survival. A. Scientists believe there may be an evolutionary reason for this difference, perhaps in symmetry in the skull and the development of echolocation. We do not think that baleen whales use echolocation or, if so, to a much more limited extent.
Humans suffer when attempting a deep dive and the dive can become fatal.
First of all, when under water, cetaceans are not breathing pressurized air as is the scuba diver. The cetacean holds its breath under water, breathing only at the surface, so there is not a constant supply of new pressurized air to be dissolved into its body. Scientists think that the deepest diving cetaceans may actually exhale before diving so that they have less air in their lungs to be dissolved under pressure. Amazingly, when a cetacean dives deep, under tons of pressure, its lungs actually collapse because there is no new supply of air to pump them up. Whales don't have to worry about excessive nitrogen getting dissolved, compressed and then expanded in their bloodstreams.