1 The prefixed verbal form is understood as a preterite, referring to the creation of the world.
2 He … established it upon the ocean currents. The description reflects ancient Israelite prescientific cosmology, which is based on outward appearances. The language also suggests that God’s creative work involved the subjugation of chaos, symbolized by the sea.

In other versions

A Psalm of David.

The earth is the Lord’s and the fullness thereof,

the world and those who dwell therein,

for he has founded it upon the seas

and established it upon the rivers.

Of David. A psalm.

The earth is the Lord’s, and everything in it,

the world, and all who live in it;

for he founded it on the seas

and established it on the waters.

A psalm of David.

The earth and everything in it,

the world and its inhabitants,

belong to the Lord;

for he laid its foundation on the seas

and established it on the rivers.

A psalm of David.

The earth is the Lord’s, and everything in it.

The world and all its people belong to him.

For he laid the earth’s foundation on the seas

and built it on the ocean depths.

A psalm of David.

The earth is Yahweh’s, with its fullness,

the world and those who live in it,

because he has founded it on the seas,

and has established it on the rivers.

A Psalm of David.

The earth is the Lord’s, and the fulness thereof;

The world, and they that dwell therein.

For he hath founded it upon the seas,

And established it upon the floods.

Public Domain