As noted above, the high towers and fenced walls refer to the great cities of the foreigners that Israel so admires. Once again, the Lord emphasizes that not only the cities, but the wealth of those places shall be brought down. The references to the ships of Tarshish and the “pleasant pictures” being references to the wealth.
“The ships of the sea” (v. 16) represent the people’s commercial enterprises, especially the “ships of Tarshish,” which were noted for their agbility to travel long distances, their strength as war vessels, and their large storage capacity as commercial carries. The “beautiful craft” (NAS) or “pleasant pictures (KJV) were apparently the pleasure crafts or ships in which the wealthy traveled throughout the Mediterranean.” (Ludlow, p. 91).