How much of the Earth’s surface does the ocean cover? The ocean covers more than 70% of the Earth’s surface. That’s why Earth is often called the “water planet.” Where and how deep is the deepest point in the ocean? The deepest known point on Earth is at the bottom of the Mariana Trench, a depression in the floor of the western Pacific Ocean, just east of the Mariana Islands. This trench is 1,554 miles long and 44 miles wide. Near its southwestern extremity, 210 miles southwest of Guam, lies the deepest point on Earth. This point— referred to as the Challenger Deep — plunges to a depth of nearly 7 miles. In 1960, the Trieste, a manned submersible owned by the U.S. Navy, descended to the bottom of the Mariana Trench. There, the pressure from the weight of the vast ocean above is tremendous. At more than 8 tons per square inch, it’s the equivalent of one person trying to hold 50 jumbo jets! How “hot” is the hottest creature on Earth? University of Delaware marine scientist Craig Cary recently discovered that an inhabitant of the deep sea is the most heat-tolerant animal on Earth. The Pompeii worm (Alvinella pompejana) can survive an environment as hot as 80° C (176°F) — nearly hot enough to boil water. The water erupting from hydrothermal vents is hotter than 100°C (212°F), yet it does not boil. Why? As vent water bursts out into the ocean, its temperature may be as high as 400°C (750°F). Yet this water does not boil because it is under so much pressure from the tremendous weight of the ocean above. When the pressure on a liquid is increased, its boiling point goes up. When was the first submarine built? Cornelius van Drebel, a Dutch inventor, is usually credited with building the first submarine. His underwater vessel consisted of a wooden frame sheathed in leather. Oars extending out the sides propelled the craft through the water, at depths up to 4.6 meters (15 ft). The oar openings were sealed with tight-fitting leather flaps. Drebel tested the sub in the Thames River in England between 1620 and 1624. King James I is said to have taken a short ride in the craft. When you see R/V before the ship name Atlantis, what do you think it means? The R/V is the abbreviation for research vessel.