As a dub, I played the "[insert miracle here]" game to justify/explain the Noah story. Jehovah miraculously brought him the animals, Jehovah miraculously put them all back where they belong. The Bible says the animals ate vegetation (doesn't it? Can't recall now) so Noah stocked up on straw for them. (Straw has little nutrition value, he probably brought hay instead. "C'mon, mouse, eat your hay now...")
He didn't need to bring fish, the Bible says only the animals on dry ground expired. (No word on how the fresh water fish and salt water fish [and cold water fish and hot water fish]) survived the mixing of their environments.)
And of course you know the dub/fundy line on how the earth was different before the flood; water canopy, shallow seas, shortish mountains, all that guff.
I even read where some believe God shrunk the animals (or Noah took baby animals) so they would all fit on the ark.
I've never heard anybody try to explain where all the animal waste would have gone. The only opening was on the top deck, so somebody had to haul it all up from two lower decks and shove it out the window. (How would you like to be a survivor, riding in a row boat, waiting to starve to death, only to have a bucket of elephant dung flung onto you!)
Of course, all of this falls completely apart when you ask, "If God was willing to open his 'miracle bag' to make the ark thing possible, why bother with the ark at all?" (Elder: "So don't ask!")
Dave