The Rainbow Islands are an archapelago that serves as the main location in the Rainbow Islands games. As shown in the various games, there are 11 known islands. Each island has its own theme, and is home to many monsters surrounding the theme.
The Rainbow Tower, the location where Bubble Memories takes place, is located on an island called Rainbow Island. It is unknown if this is a new island, Bubble Island, or unrelated to the Rainbow Islands.