Much of the Arctic Ocean is fairly shallow compared to other oceans. There must have been times in the past during severe ice ages that a lot of what is now the ocean bed was above sea level. When was the last time that most of the arctic Ocean floor was above sea level? Going back further, were there ever forests, peat bogs or coal deposits on the present day ocean floor, and when were the internationally coveted oil reserves formed?
During glaciations, the shelves down to ~100m depth would have been above sea level, but they would have been covered by ice sheets.
The actual "ocean floor" would still be deep water. There is a general explanation of the oil formation here and here, although they don't say when (or where the continents were when the sediments were deposited), and again, this is on the shelves, not the floor.