Joshua 16:3

Then it descended westward to the border of the Japhletites as far as the border of Lower Beth-horon and on to Gezer, and it ended at the Sea.

Note That is, the Mediterranean Sea, also called the Great Sea; also in verses 6 and 8

BSB · Berean Standard Bible
And goeth down westward to the coast of Japhleti, unto the coast of Beth-horon the nether, and to Gezer: and the goings out thereof are at the sea.
KJV · King James Version
and it went down westward to the border of the Japhletites, to the border of Beth Horon the lower, and on to Gezer; and ended at the sea.
WEB · World English Bible
and it went down westward to the border of the Japhletites, unto the border of Beth-horon the nether, even unto Gezer; and the goings out thereof were at the sea.
ASV · American Standard Version

Related passages

From the Treasury of Scripture Knowledge, grouped by the word they explain.

Beth-horon
Eusebius says that the two Beth-horons were twelve miles from Jerusalem, towards Nicopolis or Emmaus: of which the one, called upper Beth-horon, from its situation, was built (rebuilt) by Solomon, and the other, called nether Beth-horon, was given to the Levites. Josephus places Beth-oron about 100 furlongs from Jerusalem. Dr. Clarke mentions an Arab village called Bethoor, about twelve miles from Jerusalem, a small distance from Rama, which he supposes, from its situation on a hill, to be Beth-horon the upper.
Joshua 18:13; 1 Kings 9:15–17; 1 Chronicles 7:24, 28; 2 Chronicles 8:5
the sea
Numbers 34:6