height - imagery from the Assyrian felling of trees in Lebanon (Isa 14:8; Isa 33:9); figuratively for, “I have carried my victorious army through the regions most difficult of access, to the most remote lands.”
sides - rather, “recesses” [G. V. Smith].
fir trees - not cypresses, as some translate; pine foliage and cedars are still found on the northwest side of Lebanon [Stanley].
height of ... border - In 2Ki 19:23, “the lodgings of his borders.” Perhaps on the ascent to the top there was a place of repose or caravansary, which bounded the usual attempts of persons to ascend [Barnes]. Here, simply, “its extreme height.”
forest of ... Carmel - rather, “its thickest forest.” “Carmel” expresses thick luxuriance (see on Isa 10:18; see on Isa 29:17).