Mermaid Island was produced by Soma in 1991-1993. It was a playset containing 12 small moulded plastic mermaids, a floatable foam island and a few treasures.
Images on this page thanks to Jennifer and Sandy!
"Travel to a tropical island where pretty mermaids frolic, gemstones glitter and palm trees sway in the breeze...without leaving your bathtub! Our Mermaid Island is made of thick, dense foam so it floats on water, and it comes with 12 little mermaids, real shells, pretend gemstones, plastic trees, even a treasure chest. Decorate the Island any way you like...then let the adventures begin! Over 30 pieces: island Is 16" long x 2" high."