Following are a number of back-translations as well as a sample translation for translators of Isaiah 33:21:

• Kupsabiny: “God will show his greatness
  at that place.
  God shall stop/prevent/block the enemies
  like how broad rivers do,
  where the ships of the enemies cannot go through.” (Source: Kupsabiny Back Translation)
• Newari: “The LORD, our almighty one will live there.
  It will be a place of rivers and great rivers.
  No boat [lit.: water-ship] propelled by oars will sail [lit.: be driven] there.
  No great ships will be brought there either.” (Source: Newari Back Translation)
• Hiligaynon: “In this place the LORD will-show to us (incl.) that he is powerful. Jerusalem will- become like a place with broad/wide rivers and streams which can- not -be-crossed-over by the something-to-ride-on of the enemies.” (Source: Hiligaynon Back Translation)