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.
In printing, DPI (dots per inch) refers to the output resolution of a printer or imagesetter, and PPI (pixels per inch) refers to the input resolution of a photograph or image. DPI refers to the physical dot density of an image when it is reproduced as a real physical entity, for example printed onto paper.