What might 'unhooped oceans' mean in this passage of Melville?

I suspect it comes from the concept of contained bodies of water/beer/ wine/whisky and especially whale oil within a vessel (such as a barrel).

Empty barrels waiting to be loaded onto whaling ships of the 1800s

*note that each hoop has its own name (ex french etc) from the trade. (not covered in this post)

hoop

A circular band of metal, wood, or similar material, especially one used for binding the staves of barrels or forming part of a framework.

Lexico

So, "unhooped" would mean:

boundless

unlimited or immense.

Lexico

Also:

unrestrained

Lexico

See also: hoop (v) Etymonline:

[Edit]

It has been suggested (thank you @Flynn) that the latitude and longitude lines of a world map might also make sense....meaning "uncharted".