Salty.
There is more evidence if we take the bible literally that there was a lot more water than we see remaining on this planet today. Because in the creation event, it says God separates the waters from the waters.
Here look:
Genesis 1
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. So the evening and the morning were the second day.
So we see the waters under the heavens (seas), then the heavens, then the waters above the heavens. This is a very misunderstood piece of the bible.
But it does seem that there are waters at the outer boundaries of the universe.
Look at another scripture:
Psalm 148
148 Praise[
a] the Lord!
Praise the Lord from the heavens;
Praise Him in the heights!
2 Praise Him, all His angels;
Praise Him, all His hosts!
3 Praise Him, sun and moon;
Praise Him, all you stars of light!
4 Praise Him, you heavens of heavens,
And you waters above the heavens!
Chew on that for a while