Man has always been fascinated to explore the unknown, like the sea depths. Man has not met with a lot of success in this field.
The weight and pressure of water has been the greatest obstacle. As a body sinks deeper, the more it is crushed by pressure and ultimately, it becomes too huge and unbearable.
Thus, scientists are trying to build hulls, which can withstand greater pressure. Also, these bodies used for exploration have a very limited area for movement, limiting their actions.
Below Depths Of The Sea info from Wikipedia (Read More):-
Deep-sea exploration is the investigation of physical, chemical, and biological conditions on the sea bed, for scientific or commercial purposes. Deep-sea exploration is a relatively recent human activity, the depths of the sea are still a largely unexplored part of the planet earth.
Deep-sea exploration began when French scientist Pierre Simon de Laplace calculated the average depth of the Atlantic ocean, by observing tidal motions registered on Brazilian and African coasts. He determined this depth to be 13,000 ft (4,000 m). Deep-sea lifeforms were discovered in 1864 when Norwegian researchers sampled a stalked crinoid at a depth of 3,109 m (10,200 ft). More important discoveries have been made since 1870, the British Government sent out the Challenger expedition (a ship called the H.M.S. Challenger) in 1872 which discovered 715 new genera and 4,417 new species of marine organisms over the space of 4 years.
http://en.wikipedia.org/wiki/Deep-sea_exploration
