moving into a house with an elevated deck, with an unfinished walkout
basement underneath the deck. The decks sits up some 10-12 feet.
Underneath the deck right now is grass/dirt/mud. Pretty nasty. I
have long term visions of a finihsed walkout basement leading to a
nice patio.

However that is the future, and this is now..

is there a low cost, DIY way to clean up the area underneath the deck,
such as adding a gravel patio? If so, how would one accomplish this