Here is an expanded color palette with 8 colors inspired by petrol, green, and blue, suitable for a dark background.

json
{
  "palette_name": "Expansive Deep Waters",
  "colors": [
    {
      "name": "Petrol Blue",
      "hex_code": "
          
          #005B5C
       "
    },
    {
      "name": "Forest Green",
      "hex_code": "
          
          #2C3E50
       "
    },
    {
      "name": "Deep Sea Blue",
      "hex_code": "
          
          #1A6F8C
       "
    },
    {
      "name": "Teal Green",
      "hex_code": "
          
          #008C7A
       "
    },
    {
      "name": "Charcoal Black",
      "hex_code": "
          
          #1B1B1B
       "
    },
    {
      "name": "Midnight Blue",
      "hex_code": "
          
          #003B5C
       "
    },
    {
      "name": "Emerald Green",
      "hex_code": "
          
          #50C878
       "
    },
    {
      "name": "Slate Gray",
      "hex_code": "
          
          #708090
       "
    }
  ]
}

This palette features a harmonious blend of deep blues and greens with a touch of gray, offering a rich, sophisticated look against dark backgrounds. Each color complements the others while providing depth and contrast.

Would you like more information on how to use these colors, or perhaps need assistance with something else?