From the Encylopaedia Judia 12:996

Apart from the Isaiah 14:14-19 and Ezekiel 38:18 ff passages, the numerous bibical refferences to the netherworld are vague and inspired by Ancient Near Easter folklore. Several names are given to the abode of the dead, most common being She`ol always femmine and without the definite article - a sign of proper nouns. The term does not occur in Semite languages, except as a loan word from the Hebrew She`ol, and it's etymology is obscure. Other common designations of the netherworld are erez "earth" or "underworld" (e.g. I Sam. 28:13 ; Jonah 2:7 ; Job 10:21-22) ; qever, "grave" (Ps. 88:12) ; afar, "dust" (Isa. 26:5-19; cf Gen. 3:19) ; borr "pit" (e.g. Isa 14:15 ; 38:18 ; Prov. 28:22) ; shahat , "pit" (Ps. 7:16) ; `avaddon "Abaddon" (e.g. Job 28:22) ; dumah (apparently= "the place of abbiding" ; Ps. 94:17 ; 115:17) ; nahale beliyya`al (the torrents of Belial" ; II Sam. 22:5) ; "the Nether parts of the earth" (Ezek. 31:14) ; "the depths of the pit" (Lam. 3:55) ; "the land of the darkness" (Job 10:21).
The Netherworld is located somewhere under the earth (c.f.
Num. 16:30 ff) or at the bottoms of the mountains ( Jonah 2:7), or under the waters - the cosmic ocean (Job 26:5). It is sometimes personifed as a voracious monster with a wide-open mouth (e.g. Isa. 5:14 ;; Hab. 2:5 ; Prov. 1:12), Kings nobles and pauper, master and slaves are equal in She`ol (Job 3:13 ; Ezek. 32:18-32). For Israel's neighbors, the rule of the universe was divided amoung various deties, and the netherworld was the dominion of a pair of infernal gods. For Israel, however, the Lord rules over the whole universe, His sovereignty extends from heaven to She`ol (Ps. 139 ; Job 26:6 ; cf. Ps. 90:2 ; 102:26-28). However, there is no communication between the dead and the Lord (Ps. 88:6) ; no praise to the Lord comes from the netherworld (Isa. 38:18 ; Ps. 30:10 ; 88:12-13)

Gehenniom || Paradise