Challenges Undersea

Look at ways humans have overcome water pressure, temperature, and lack of oxygen to function under water.

Water Pressure - As a person travels deeper in the ocean, water pressure increases so much that at some depths a human would be crushed from the pressure. To prevent death and allow for exploration in deep waters, the bathysphere was designed. Built with steel hulls, the bathysphere maintains normal air pressure while operating at depths of 3,000 feet. Using a bathysphere people are able to explore safely.

Explore how deep the Navy's submersibles dive using this charting activity.

Think About It! If the pressure increases as one descends in the ocean, what do you think living creatures in the deepest part of the ocean look like?

Temperature - As sunlight enters water, different wavelengths are absorbed by the water. The red wavelengths warm the upper layers. Descending further, at a depth of a few hundred feet, only a few rays of blue and green light remain and the water becomes cooler. Divers need protection from the cold. A wet suit lets in some water and keeps the diver warm by using body heat to warm the water and create a layer of insulation. An inflatable suit includes an insular dry air suit that maintains a comfortable temperature by pumping air to the diver through cords connected to a surface ship.

Think About It! Sunlight does not reach the deepest parts of the ocean. As explorers go deeper and deeper, the water becomes colder and inky black. Can you imagine the explorers' surprise when they discovered luminous plant and animal life at these great depths?

Breathing - One of the largest obstacles in exploring the oceans is breathing underwater. Explorers have developed two methods. Manned submersibles enable divers to descend to great depths in an artificial atmosphere. For free divers, those outside of a ship or untethered to a ship, breathing for long periods underwater requires a supply of oxygen. The invention of SCUBA (self-contained underwater breathing apparatus) provides divers with a tank of oxygen or mixed gases and a safe breathing device enabling them to work at depths of 500 feet and remain underwater for greater periods of time.

Think About It! Before the invention of scuba gear people dived in the ocean for extended periods of time. How were they able to breathe?

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