Far out on the continental shelf below hundreds of feet of water are very large canyons. How did they get there? Perhaps the ocean level was much lower in the past allowing canyon carving offshore. This fits nicely with the Biblical Flood. During the Flood, the whole earth was covered by water. According to Psalm 104 (NAS), the mountains rose up and the valleys sank down. Water filled the oceanic trenches to a great depth lowering the global sea level. Other large bodies of waters rose up with the mountains to become giant inland lakes and seas. These would keep the sea level much lower until they drained (forming canyons). After the flood, great bodies of ice formed during the ice age which also greatly lowered the sea level.