Just following up on what ascanius said about oceans, the deepest part of the ocean is in the Mariana Trench, it's just under 11000m deep. The whole ocean averages about 3688 m deep though. You probably don't have to map out the entire ocean floor, but hopefully that little tidbit can help you with the bits you do map!
Everything you've done so far is super awesome and in-depth; it was actually this thread that inspired me to finally make an account and get grinding out my own world map! So uh, thank you