Secular scientists are unclear as to the origin of anything: the universe, our solar system, the earth, the oceans, or the creatures that inhabit the oceans.
Where did the oceans come from according to evolutionists? Baby boomers may remember this "just-so story" described in the popular Time-Life book series (that includes a veiled swipe at the Biblical explanation while bowing to naturalism).
Finally the day came when the falling raindrops did not hiss away in steam, but stayed to start filling the crevices and corners of the naked planet. Then it rained, and the accumulation of the seas began. The accumulation did not take place (in the opinion of modern geologists) through "the greatest deluge of all time" that has so often been described. So far as anyone can tell, it may merely have rained as it rains today. Nature has plenty of time. It probably took a billion years to fill the oceans [emphasis added].1
Do secular scientists have any better ideas today? "The origin of the water in the oceans is unclear" states the University of New South Wales School of Environmental Sciences.2
For decades many planetary scientists believed that the ocean's water may have come from a rain of comets (so to speak) laden with water. But a 1999 Caltech study by a cosmochemist and his team threw a wet blanket on this theory when they measured significant amounts of "heavy water" (HDO) from the Hale-Bopp comet.3 This type of water contains deuterium, a heavier isotope of hydrogen having one neutron and one proton in the nucleus. If the "oceans-from-comets" theory is correct, our oceans should be deuterium-rich. They are not.
What do creationists say regarding the origin of the oceans? We look to the Biblical model and find that our planet began cool and covered with water (see Genesis 1:2) as opposed to the secular model stating it was molten rock with no water! On the third day of creation, the waters under the heaven were gathered into one place which God called Seas (see Genesis 1:9-10). Centuries later, at the Flood, He again covered the land with water, until the fountains of the deep were closed and the water receded steadily from the earth. As the fountains closed, the ocean floor sank, forming new and much deeper ocean basins (such as the 36,163 foot deep Mariana Trench), permitting the continents to drain and emerge from the waters.
Today's oceans eloquently testify to God's creative power, His judgement at the Flood, and His provision today.