Psalm 107 is is a liturgical type psalm according to Westermann and others: there is clearly an introduction, four “stanzas” each with its own thanksgiving chorus, and the entire psalm is closed with all the people voicing praise together for Yahweh’s wondrous works (pala) of deliverance. This is his loyal love (hesed) on display.
In verse 3, the psalmist mentions how Yahweh’s hand brought his people back from North, West, East, and the Sea (check the footnotes of your English Bibles – the Hebrew root there is yam [sea] rather than the BHS/BHK proposed yamin [south]). Each section of the psalm then goes on to describe peril on the four corners of the world: 1) the hot East desert, 2) The dark West bondage [prison], 3) the illness [punishment] from the North and 4) the depths of the seas.
Each one of those four (as verse 3 introduces them) is laden with OT imagery. To list a few – East – the hot, scorching, life-draining judgment sarab (sirocco) winds (cf. Is 27.8, Jer 4.11-12, Ezek 17.10, Hos 13.15, etc); West – the cold setting of the sun, darkness away from Yahweh (Gen 15.12, Ps 104.19-20, Is 45.5-7, etc); North – the poured out judgment resulting in “sickness” (Jer 1.13-14, 50.41-42, 47.2-4, etc); and the Sea – the watery chaos of judgment or distance from God (Jonah, Is 17.12, Jer 6.22-23, 50.41-2, etc). It is interesting to try to tie these four deliverance episodes in with other OT episodes – you can and you can’t. Perhaps they are generalized to portray several, instead of a one-for-one correspondence.
Of course more can be said (go for it!), but in summary, this Psalm is great poetic theology: Yahweh is not only everywhere vertically (Ps 139 – heights/depths), he is also present at the far corners of the world (horizontal imagery). He can go to the desert to deliver, to the far sea to rescue, and to the far North and East to rescue rebels. The many fours in this Psalm represent four types (all kinds) of people, four types (all kinds) of misery/distress, and four types (all sorts) of rescues. In a word, Yahweh is powerful over all creation to save people from anywhere who cry out in any sort of distress. There are scores of other OT and NT texts that say the same thing in a different way. This is a poem that essentially says in graphic, imaginative terms: whoever calls on the name of Yahweh will be saved.
Note: See John Jarick, “The Four Corners of Psalm 107″ The Catholic Biblical Quarterly #59, (1997), 270-287 for a great detailed discussion of this theme.
Also, HT for the map goes to strangemaps.wordpress.com (click here to see the above map). If the above map had four extensions on it, it would portray Psalm 107 quite well. See the center? The center of the map is the one who in the last verse of Psalm 107 is wise: he is wise who stands in the center in Yahweh’s presence, meditating on how God has brought him from a corner to the “center,” near God.