This includes holding the fish in water deep enough to submerge its gills. Chinese softshell turtles often submerge their heads in water. Proper habitat requires enough water to submerge in and grass nearby. Water continues to submerge decks and more explosions occur. First, the paleontologist must submerge the egg in a very dilute phosphoric acid bath. The ocean will then completely submerge Midgard. His design used leather bags that could fill with water to submerge the craft. Submarines have controllable buoyancy to make them submerge and rise on demand. Such floods cause rivers to burst their banks and submerge homes. Although their viewports are below water level, the "submarines" do not actually submerge when "diving". They place sticks on their snouts and partly submerge themselves. The farmer's daughter challenges the "kappa" to submerge several gourds in water. The aliens submerge in the chemical and combine to grow into a single large alien. This meant that the submarine could not submerge again. Recent research which contradicts the claim that rising sea levels will necessarily submerge island nations.