Not a great idea, but...
Never go straight down or straight up
@GonMoose the Great, unless you're building, then straight up is okay. Also, spiraling straight down is okay, as long as you never break a block directly under you.
@GonMoose the Great, it's the golden rule of Minecraft
@GonMoose the Great, just stand between two blocks. Then min down on one, then the other. Easy peasy
And now you lost ypur diamond pickaxe you scrub
You drink fire resistance potion and water bucket and digging straight down is great