What are the main underwater ocean ridges?
821171
What a fascinating subject. This map gives you their names and positions. \n\nhttp://ocean-ridge.ldeo.columbia.edu/general/html/home.html\n\nI hope this helps! :)
713812
Challenger Deep of the Mariana Trench  (or Marianas Trench) is the deepest part of the earth's oceans, and the deepest location of the earth itself. The bottom of the trench (Challenger Deep) is farther below sea level than Mount Everest is above it. The trench has a maximum depth of 10,911 meters (35,798 ft) below sea level. Some says it is 11,033 meters (36,201 feet) deep. It is located in the floor of the western North Pacific Ocean, to the east and south of the Mariana Islands  near Guam and Japan  under the Philippine Plate.♥
681024
There have been a number of trips to the deepest part of the ocean, the Marianis trench-Though, more to the point of your question, the great majority of the ocean bottom remains unexplored, and it's likely that there are a great many animals that have never been observed alive.  There are a lot of great stories about undersea civilizations-or intelligent colonies of giant squid..but like you say..who knows what we'll find?
182560
The average depth of the oceans is about five times the average elevation of the land. In general, the continents stand about three miles above the ocean floor. According to the National Geographic Atlas, the deepest-known part of the ocean measures [10,924] meters (35,839 feet), in the Marianas Trench near Guam. If the world's highest mountain, Mount Everest (29,141 feet), were to be placed into this trench, it would be covered by over 1.25 miles of water.
544324
I like your list.\nMine is the Pyramids, Norwegian fjords, and Antarctica
120196
Try a Yahoo Search for:\ntopographical map ocean floor\nhttp://search.yahoo.com/search?p=topographical+map+ocean+floor&ei=UTF-8&fr=slv1-&x=wrt\n\nThis site has some maps available online however I think that is available online is not going to get you the resolution you are looking for:\nhttp://www.ngdc.noaa.gov/mgg/announcements/announce_predict.html\n\nHere's the most detailed I could find:\nhttp://www.ngdc.noaa.gov/mgg/image/2minsurface/1350/45N045W.jpg\n\nThis site is just so darned interesting to explore.  Found:\nhttp://www.ngdc.noaa.gov/mgg/ibcm/ibcm.html\n\nhttp://modb.oce.ulg.ac.be/medmex/topographic.html\nhttp://pubs.usgs.gov/bul/b2016/chapb/ch_b.html\n\nhttp://earthobservatory.nasa.gov/Newsroom/NewImages/images_topic.php3?img_id=16350&topic=oceans
542089
Facts about the Oceans\nArea: about 140 million square miles (362 million sq km), ore nearly 71% of the Earth's surface.\n\nAverage Depth: 12,200 feet (3,720 m).\n\nDeepest point: 36,198 feet (11,033 m) in the Mariana Trench in the western Pacific.\n\nMountains: The ocean ridges form a great mountain range, almost 40,000 miles (64,000 km) long, that weaves its way through all the major oceans. It is the largest single feature on Earth.\n\nHighest Mountain: Mauna Kea, Hawaii, rises 33,474 feet (10,203 m) from its base on the ocean floor; only 13,680 feet (4,170 m) are above sea level.
178423
Its average depth is 4,280 m (14,040 ft). The greatest known depth in any of the world's oceans is 11,033 m (36,198 ft) in the Mariana Trench off Guam.
593
(deepest oceans and seas)\ndot\n#1 Pacific Ocean (35,837 ft) (10,924 meters)\n#2 Atlantic Ocean (30,246 ft) (9,219 meters)\n#3 Indian Ocean (24,460 ft) (7,455 meters)\n#4 Caribbean Sea (22,788 ft) (6,946 meters)\n#5 Arctic Ocean (18,456 ft) (5,625 meters)\n#6 South China Sea (16,456 ft) (5,016 meters)\n#7 Bering Sea (15,659 ft) (4,773 meters)\n#8 Mediterranean Sea (15,197 ft) (4,632 meters)\n#9 Gulf of Mexico (12,425 ft) (3,787 meters)\n#10 Japan Sea (12,276 ft) (3,742 meters)
975488
When plates are diverging they are pulling apart and magma can come up from under the crust to fill the gap. This can create mid-ocean ridges, like the Mid-Atlantic Ridge, which is an underwater mountain range that runs about the whole length in the center of the Atlantic ocean.
462483
The Challenger Deep is the deepest known point in the oceans, 10,911 meters (35,797 feet) deep at its maximum\nSource(s):\nhttp://en.wikipedia.org/wiki/Challenger_Deep
1049053
The deepest point in the ocean is the Mariana Trench located in the Pacific Ocean near the Northern Mariana Islands. It has a maximum depth of  (35,838 ft) It was fully surveyed in 1951 by the British naval vessel, "Challenger II" which gave its name to the deepest part of the trench, the "Challenger Deep".Much of the bottom of the world's oceans is unexplored and unmapped. A global image of many underwater features larger than 10 km was created in 1995 based on gravitational distortions of the nearby sea surface.
47013
The deepest point measured in any ocean is the Marianas Trench, in the Pacific Ocean.  On March 24, 1995, the Japanese probe Kaiko recorded a depth of 10,911 m (35,797 ft), the most accurate measurement yet taken.
330014
Lithosphere (most)\nHydrosphere\nBiosphere\nAtmosphere (least)\n\nwould be my guess
193190
Currently there are over five thousand active volcanoes underwater varying from ones larger than any on the surface to cones no larger than an automobile. The net reslut of this action is thermal heating of the oceans, at key positions, which in turn reaches the surfaceto be carried aloft into the atmosphere to become part of our surface weather pattern system. As the oceans are heated winds of a high velocity are created and driven over the land areas due to temperature differential. \n\nIn the Pacific Ocean there are ocean basins - volcanoes, of which there are estimated to be about 20,000 on the ocean bottoms of the world. Some of these form single mountains, and others join with other volcanoes to form ridges. The highest ones rise above the surface of the water as islands, which in many cases linear groups such as the Hawaiian Islands. \n\nIsland groups are simply the highest summits of ridges. The submerged part of the Hawaiian Islands is among the largest and longest of these volcanic ridges--more than 1,500 miles (2,400 kilometers) long. \n\nMany island groups of the Pacific are linear in form, with the largest and highest island of the group at one end and the lowest and smallest at the other. This feature is true of the Hawaiian Islands, explained as the result of intermittent movement of the tectonic plate over what is called a hot spot. \n\nMolten volcanic material is ejected from it and results in the formation of a large mass of material if the plate pauses for a sufficient length of time at the spot. In this way a volcanic island, or ridge, is built. The plate moves, and another part of it lies over the hot spot, receiving fresh volcanic material. Meanwhile the older material, if it has become an island, is subject to erosion and thus is worn down.
886690
Regardless as to where? Mindanao Deeps (7mi straight down)\nLowest dry place - death valley\nLowest continental place - Bottom of the dead sea.\n\nThe marianas are in the pacific and the trench is part of the complex call the mindanao deeps.
186157
Deepest Point in the World (and Pacific Ocean)\nChallenger Deep, Mariana Trench, Western Pacific Ocean: 35,840 feet / 10,924 meters\n\nLowest Point in the World (and Asia)\nDead Sea shore, Israel-Jordan: 1369 feet / 417.5 meters below sea level