Earth Science: Geology, the Environment, and the Universe

Chapter 16: The Marine Environment

Problem of the Week

The Final Frontier

Have you ever heard space referred to as the final frontier? How about the last great unknown left for the explorer? Well there are many scientists, like Sylvia Earle, a former chief scientist at the National Oceanographic and Atmospheric Administration, who see the oceans as the final frontier. In fact, Earle thinks, "there's a perception that we have already explored the sea," but that "the reality is, we know more about Mars than we know about the oceans". This perception may be a result of a growing awareness of the fragile nature of the oceans, but there is still a great deal to be discovered and learned.

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Bathysphere William Beebe

NASA: Ocean Planet

The conditions encountered during the exploration of the abyssal depths of the oceans are as hazardous, and foreign to humans, as are the conditions in space. There is no light, the temperatures are frigid, and the pressures are intense. To travel there, humans must create an artificial environment, just as we must do to travel in space. Only in the deep ocean, it must be more than a suit. In 1951, the bathyscaph Trieste took two men 35,800 feet (10,740 meters) down to the deepest spot in the oceans - the Mariana Trench's Challenger Deep, southwest of Guam in the western Pacific. Until 1995, there had been no return to those depths, and even then it was via a remotely controlled submersible. So the depths remain relatively unknown biologically, physically, and ecologically.

Think About This:

As mentioned earlier, the conditions deep in the ocean are inhospitable. The lack of light, the intense cold, and extreme pressure are all factors that inhibit exploration, and for the creatures of the deep, these factors make for very interesting living conditions.

If you were an organism living at these depths, what adaptations might you need in order to survive? Brainstorm a bit about this question. Then go check out these Web sites to see some of the organisms that live in the abyssal depths of the oceans.

The Problem:

One of the greatest challenges the deep ocean presents to human explorers is the extreme hydrostatic pressure at great depths. Hydrostatic pressure is caused by the pressure of the water column, pressing down and in onto an object. This is similar to atmospheric pressure studied several chapters earlier. Going back to that chapter’s problem, we found out that there were 14.7 pounds per square inch (psi) pressing down on an object at sea level (or one atmosphere of pressure). This is the standard commonly used by divers for measuring pressure, so it will be used in this problem instead of an SI unit. In the ocean one additional atmosphere of pressure is experienced for every 33 feet (9.9 meters) descended. At 33 feet below sea level, the hydrostatic pressure would equal the air pressure at sea level + another atmosphere of pressure (14.7 psi + 14.7 psi = 29.4 psi).

*Check this site to see how far down aided and unaided man and machine can travel –

  • Suppose that you traveled in a deep sea submersible to the bottom of the Mariana Trench. What would the hydrostatic pressure be at 35,800 feet (10,740 meters)?

  • What type of structural and design features might your submersible need to have to withstand the pressure at such depths?

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