The answer is: Whale

Gen 1:21 - The NIV renders this as 'great sea creatures'.

In the Genesis creation narrative, a distinct mention of "great sea creatures" gives us insight into one of the remarkable facets of the biodiversity that emerged during creation. While our modern translations often opt for the word "whale," the Hebrew term used in the text is more expansive and can signify various large sea creatures, potentially including everything from gigantic fish to mythical leviathans. It gives a sense of the majestic and the mysterious, evoking a vast world beneath the waves.

Interestingly, many cultures throughout history have myths revolving around sea creatures that play pivotal roles in their stories of creation and chaos. This wide-ranging significance adds an intriguing layer of universality to the biblical text, bridging it with global mythos—consider the great dragon of the deep, Tiamat, in Babylonian lore or the Norse Jörmungandr, the world serpent.

Moreover, the emphasis on marine life reflects a celebration of the complexities and wonders of the natural world, a theme echoed through various scriptures. The writer of Psalms, for example, opens a window into that appreciation when declaring, “What the Lord made is very good” (Genesis 1:31), artistically reminding us about the intricate balance of ecosystems where these massive creatures thrive. Making the ocean sound a continuation of God’s creative masterpiece, we are called not just to wonders from this passage but to respect and safeguard the magnificent life swimming beneath the waves.