So named because it’s near the Marianas Island chain in the Pacific Ocean, this is the deepest known part of the ocean. A chasm so deep you need to see this image to appreciate it. Make sure you click on the image to enlarge it. Then scroll down.
And only 10% of the oceans have been mapped. So there may be a deeper crevice than this. Imagine flying high across the country on jet plain and looking down from the window above. If you have ever done that, remember how small everything looked. That is still not the distance to the bottom of the Mariana trench.