Some of these responses are hilarious, yet some have a bit of accuracy. For the man who asked the question... never believe anything seen on TV. Ever.
Have divers been to depths greater than 100m, 200m? Absolutely. Does it require a monumental amount of time, money, planning, and training? You bet. Not just the decompression, but the acclimation to the pressures prior to the dive, and handling life under these pressures is also vital to the job. It is true that most of the body is made of incompressible tissue and liquids... ie. blood, bone, muscle, interstitial fluid, inter/extracellular fluid, lymph, brain, etc etc etc... but within all of this is dissolved gases; nitrogen being the most abundant and is not metabolized by the body.
decompression at any depth for any amount of time is required by your body to rid of these gases properly so as not to accumulate in a part of your body and become "trapped" which can cause all sorts of ailments. longer deep dives, Type 2 decompression sickness is most common, whereas shallow dives arterial gas embolisms are the most common. all are severe and all are potentially deadly. The degree to which a person may be susceptible or even affected is different for each case.
The deep diving is done by those known as "saturation divers". This is a term given to those that dive very deep for extended periods of time. The time at depth is so long that their body is literally completely saturated with the maximum amount of dissolved gases that can be compressed at the given depth. Where you are currently sitting to read this is where you live within a few feet of elevation... you have been there for a long time. You are saturated. To go up in elevation requires off-gassing. Ever heard of altitude sickness? Same thing for a diver who comes up form the depths, only at a much greater scale due to the pressures of water versus air. the deep and longer under, the longer decompression required. In-water decompression is possible, though surface decompression (SUR-D) is the preffered method due to controlling the environment.
How do I know what I am talking about?
I was also a Navy Diver myself and was stationed in Panama City where the Navy Experimental Dive Unit is located. The two story dive chamber there is designed to crush a diver to extensive pressures equivalent to more than 700 feet of sea water. It is the same facility where the infamous Carl Brashear (Men of Honor was made after him) made one of the deepest dives recorded. Most of these divers suffer long term effects of diving that deep...
A good friend of mine teaches submariners to escape a submerged vessel in emergency and how to survive. Ho-Ho-Ho is the chant on the way up. It is a way to steady your exhalation and let out enough air to keep your lungs from popping from the reduction in pressure as you ascend the water column (Boyles Law) and not run out of air before making it to the surface. A submarine is further designed to make emergency surfacing possible via "chicken" switches i nthe event the vessel is compromised.
Another friend was stationed in San Diego with Consolidated Dive Unit (same guys that were cast in Men of Honor as the divers) that owns the 1 atmoshphere suit. It is capable of making dives far deeper than anyone might think is possible. that number is for me to know and you to only speculate...
There is much more detail to diving than just going down and coming up. rule of thumb... 30 feet per minute on a dive that does not require decompression. If so, consult the U.S. Navy Dive Manual for which all diving is referenced.