Following are a number of back-translations as well as a sample translation for translators of Isaiah 57:20:

• Kupsabiny: “But the people who are sinners are like
  an ocean that is moving to and fro,
  an ocean where water does not stand still,
  one that spits/casts up mud and bad smelling things.” (Source: Kupsabiny Back Translation)
• Newari: “But as for those who are evil, [they] come up like waves of the ocean,
  which do not remain quiet, [but] which wash up stained and polluted sewage water.” (Source: Newari Back Translation)
• Hiligaynon: “But the wicked-ones have no peace; they are like a rough/[lit. wavy] sea which carries rubbish and dirt to the side.” (Source: Hiligaynon Back Translation)