General Information:

Yahweh continues speaking.

the sea, and all that is in it, the coastlands, and those who live there

"and all the creatures that live in the sea, and all those who live on the coastlands"

This refers to the people who live in the desert and the cities. (See: rc://en/ta/man/translate/figs-metonymy)

This is a city north of Arabia. See how this was translated in Isaiah 21:16

"the inhabitants of Sela." Sela is a city in Edom. (See: rc://en/ta/man/translate/translate-names)