Occurences
The Hebrew word mearah (Strong's #H4631) is translated as "cave" or its plural 36 times in the King James Bible's Old Testament. It is also translated as "den(s)" in Isaiah 32:14 and Jeremiah 7:11. The Hebrew chor (#H2356), which means a cavity, socket or den, is also translated as "caves" in Job 30:6.
Isaiah 2:19, an End Time prophecy, is unique in the Old Testament as it is the only verse that references caves twice using two distinct words. It uses the Hebrew mearah but also mechillah (#H4247), a word which means an excavated cavern or cave.
And they shall go into the holes (mearah) of the rocks, and into the caves (mechillah) of the earth for fear of the Lord and for the glory of His majesty, when He arises to shake terribly the earth. (Isaiah 2:19, HBFV).
An Infamous Example
The Bible's first mention of caves infamously involves Lot and his two daughters. After fleeing the destruction of Sodom and Gomorrah they find refuge on a mountain near Zoar. It is while staying in this remote location that the daughters, fearful that humanity has been wiped out (Genesis 19:31 - 32), commit incest with their father.
And Lot went up out of Zoar, and lived in the mountain, and his two daughters with him . . . and he and his two daughters lived in a cave. And the firstborn said to the younger, "Our father is old . . . come, let us make our father drink wine, and we will lie with him, so that we may preserve the seed of our father." (Genesis 19:30 - 32, HBFV throughout).
Burial of the Righteous
The first recorded use of these geological structures for burial purposes took place after the death of Abraham's beautiful wife Sarah. Though greatly mourning his wife's passing, he purchases near Hebron a cave and its surrounding land as a final resting place for his beloved mate. This sadly-made four hundred shekel purchase (Genesis 23:3 - 18) is also the first mention of a financial transaction in Scripture.
Abraham buried Sarah his wife in the cave at the field of Machpelah before Mamre, which is Hebron, in the land of Canaan. (Genesis 23:19).
The cave Abraham purchased would become his own burial location (Genesis 25:8 - 10), as well as for his son Isaac and wife Rebekah, along with grandson Jacob (Israel) and wife Leah (49:29 - 32). The "tomb of the patriarchs" as it is now called, located in the heart of old Hebron, is the second holiest site in Judaism (Wikipedia).
Hidden Homes
The Horims (also called Horites) were a group of people who lived in caves in and around Mount Seir. Their name, in Hebrew, literally means "cave dweller" or "troglodyte" (Strong's #H2752). They were one of the many peoples overcome and plundered by Chedorlaomer's forces as he traveled down the King's Highway during the time of Abraham (see Genesis 14:1 - 6).
The Horims, more than a century later, are overcome by Esau (Jacob's brother) and his descendants. They are kicked out of their homes (Genesis 36:8, Deuteronomy 2:12, 22) with their land becoming Edomite territory. It is this territory that will one day give rise to Herod the Great's ruling dynasty. The name of Herod's father, Antipater I the Idumaean, means "from the land of Edom."
A Safe Haven
By far the greatest use of caves in Old Testament times were as temporary places of shelter or as locations where people could hide.
Five Amorite kings, during the time of Joshua, agreed to fight against the city of Gibeon as punishment for it making peace with Israel. Their alliance caught God's attention and led to their armies being soundly defeated by Joshua's forces. The five kings, however, were able to slip away from the battlefield and hide in a cave. Their hideaway was soon discovered and the kings were executed (Joshua 10:1 - 26).
God, during the time of the Judges, allowed the Midianites (and some of their allies) to dominate His people for seven years. They harassed Israel by taking whatever crops they wanted and destroying what remained (Judges 6:1 - 6). Their oppression was so severe that some of the Israelites resorted to living in and hiding their food in caves!
A man named Obadiah, who was the supervisor over evil King Ahab's house, hid 50 prophets each in two of these structures. He did this to hide them both from the king and his wicked wife Jezebel (1Kings 18:3 - 4).
King David
David used this natural structures several times during his life. He utilized one at Adullam to escape from King Saul who had grown to hate him (1Samuel 22:1). His location, however, once discovered attracted 400 men to his cause (verse 2).
Sometime later Saul gathered 3,000 soldiers and began to hunt for David in the desert of En Gedi. Unbeknownst to him, as he entered a cave to relieve himself, David and his men were hiding in the depths of the den. The future Israelite king resisted the temptation, however, of easily killing Saul out of obedience to God.
"Behold, your (King Saul's) eyes have seen this day how the Lord had delivered you today into my hand in the cave. And one said to kill you. But I had pity on you. And I said, 'I will not put forth my hand against my lord, for he is the Lord's anointed.'" (2Samuel 24:10).
The Philistines, shortly after learning David was accepted as the new king over all Israel, gathered their forces to seek and destroy him. David, after learning what his enemy was doing, moved temporarily to a cave (called "the hold" in 2Samuel 5:17 KJV) in order to prepare his battle plans. God ultimately gave him the victory over this implacable enemy (2Samuel 5:17 - 25).
Conclusion
Caves have, without a doubt, played a hidden but fascinating role in Biblical history. To research still more uses of these Old Testament geological structures that are not covered in this article, please see 1Samuel 13:6, 1Kings 19:9 - 13, 2Kings 13:20 - 21 and Ezekiel 33:27.