so they would not spread beyond their boundaries.

I was there when he set the limits of the seas, so they would not spread beyond their boundaries.
God blessed two groups of living creatures at creation: the fishes and the birds, the human beings, male and female in God’s own image. Then He blessed them. God created other things as well: day, night, heaven, earth, seas, grass, fruit trees, sun, moon, stars, animals and other living creatures on earth. But the Bible recorded in Genesis God blessed two groups as quoted below.

Genesis 1:22,28 New King James Version (NKJV)
Fishes and birds: 22 And God blessed them, saying, “Be fruitful and multiply, and fill the waters in the seas, and let birds multiply on the earth.”
Human beings made in the image of God: 28 Then God blessed them, and God said to them, “Be fruitful and multiply; fill the earth and subdue it; have dominion over the fish of the sea, over the birds of the air, and over every living thing that moves on the earth.”

Why? What do they have in common that other creatures do not have?
Looking at the fact that each has its own domain of operation, we can note the distinct demarcation: fishes in the seas (water), birds in the sky, humans on land. God has granted humans dominion over the whole earth at creation.

There is a word repeatedly used by God in the creation process. “Divide/Separate”. In Genesis 1:3-18 (Quoted in parts) God again makes distinction between two opposite realms: light and darkness, day and night, heaven and earth, dry land and seas.

1:3 Then God said, “Let there be light”; and there was light. 4 And God saw the light, that it was good; and God divided the light from the darkness. 5 God called the light Day, and the darkness He called Night. ..

6 Then God said, “Let there be a firmament in the midst of the waters, and let it divide the waters from the waters.” 7 Thus God made the firmament, and divided the waters which were under the firmament from the waters which were above the firmament; and it was so. 8 And God called the firmament Heaven. ..

9 Then God said, “Let the waters under the heavens be gathered together into one place, and let the dry land appear”; and it was so. 10 And God called the dry land Earth, and the gathering together of the waters He called Seas. And God saw that it was good.

14 Then God said, “Let there be lights in the firmament of the heavens to divide the day from the night; …17 God set them in the firmament of the heavens to give light on the earth, 18 and to rule over the day and over the night, and to divide the light from the darkness. And God saw that it was good.

Why does God make such clear demarcation between light and darkness, heaven and earth, land and seas? Verse 14 gives us an indication, “Let there be lights in the firmament of the heavens to divide the day from the night; and let them be for signs and seasons, and for days and years;” I believe the distinction is landmark, to guide the whole human race as an entity in survival on this the earth, and each person as to the span of his/her life on earth.

Landmark is a physical guide for a traveler. The Apostle Peter described Christians as sojourners/travelers.

1 Peter 2:11-12 (NLT)
Living Before the World
New Living Translation
Dear friends, I warn you as “temporary residents and foreigners”(Sojourners) to keep away from worldly desires that wage war against your very souls. 12 Be careful to live properly among your unbelieving neighbors. Then even if they accuse you of doing wrong, they will see your honorable behavior, and they will give honor to God when he judges the world.

God wants His people to be different and make a difference in the fallen world. He has set landmarks which guide us. This is what He said, “Do not remove the ancient landmark which your fathers have set.” (Proverbs 22:28)

A WARNING ABOUT REMOVING BOUNDARIES/LANDMARKS
Deuteronomy 19:14 [ Property Boundaries ] “You shall not remove your neighbor’s landmark, which the men of old have set, in your inheritance which you will inherit in the land that the Lord your God is giving you to possess.
Hosea 5:10 “The princes of Judah are like those who remove a landmark; I will pour out My wrath on them like water.

EVEN THE SEAS HAVE BOUNDARIES WHICH THEY ARE FORBIDDEN TO CROSS OVER
Proverbs 8:29 I was there when he set the limits of the seas,
so they would not spread beyond their boundaries.
And when he marked off the earth’s foundations,

Psalm 104
6 …The waters stood above the mountains.
7 At Your rebuke they fled;
At the voice of Your thunder they hastened away.
8 They went up over the mountains;
They went down into the valleys,
To the place which You founded for them.
9 You have set a boundary that they may not pass over,
That they may not return to cover the earth.

Jeremiah 5:22 New King James Version (NKJV)

22 Do you not fear Me?’ says the Lord.
‘Will you not tremble at My presence,
Who have placed the sand as the bound of the sea,
By a perpetual decree, that it cannot pass beyond it?
And though its waves toss to and fro,
Yet they cannot prevail;

Though they roar, yet they cannot pass over it.

Are there boundaries in the spiritual realms? The answer is yes. In the Book of Daniel, the angel Gabriel told Daniel that he was delayed by the prince of Persia and prince of Greece and angle Michael had to come to his aid so e could come to Daniel in answer of Daniel’s prayer. Apostle Paul also mentioned the existence of such territorial and hierarchical spiritual rulers of darkness and hosts of wickedness in the heavenly places (Ephesians 6:12) Revelation 12 described a war broke out in heaven: Michael and his angels fought with the devil and his angels. “but they did not prevail, nor was there a place found for them in heaven any longer. So the great dragon was cast out…”(12:7-9)

In summary: God sets boundaries to separate. Do not cross them. Do not allow breaking down of such boundaries. That was why Nehemiah and his team returned to Jerusalem in 444BC to rebuild the walls. There is spiritual significance in walls. They are landmarks for demarcation and distinction.