 Another former volcanic island lying west of Molokai was completely submerged, and covered with a cap of coral; it is now known as Penguin Bank.The sea floor between these four islands is relatively shallow, about deep, and all of the islands except Kahoolawe were joined during the low sea levels of the last glacial maximum, about 20,000 years ago.But at the outer edges of former Maui Nui, as with the edges of all Hawaiian Islands, the sea floor plummets to the abyssal ocean floor of the Pacific Ocean.