Previously you could only unlock the Tropical Romance Island and Tropical Rainforest during the community events but now you can unlock both with simoleons!
To unlock click on the sea voyage boat and click buy on the magical rainforest or tropical romance Island.
Once you unlock them you can access the island but you will still need to pay to unlock everything.
NOTE: if you already unlocked the rainforest and tropical romance island and some of the places on them you will only have to buy/build the ones you didn't manage to unlock during the events.
One Man's Trash Is Another Man's Treasure