Only a handful of people have traveled to such staggering depths. One of them is movie director James Cameron, who using a state-of-the-art vessel, dropped 35,000 feet, or about 7 miles, to the deepest place on Earth -- the Challenger Deep in the western Pacific Ocean.
DPI stands for dots per inch. Depending on the mouse make it will have certain presets (e.g 3000, 6000) and pressing it will cause your mouse to cycle through them. The higher the DPI , the farther the cursor on your screen will move when you move the mouse.
DPI means Dots Per Inch and tells the number of printed points (dots) per inch. PPI means Pixel Per Inch and tells the number of pixels per inch. DPI and PPI are basically the same, except PPI is the more correct designation, and DPI only applies to certain printers and printing methods.