These little mermaid things are addictive, and my daughter and I have been actively collecting them. They are very small (about 2 1/2 inches). If you have the mermaids, you need the pool. My 4-year old daughter spends a lot of time sliding the mermaids down the slide to splash in the pool, which holds a good amount of water to spill on your floor. Fizzing a shell in the water produces a large amount of foam which is rather entertaining. Use hot water for best results. The two pool chambers are only separated by a thin wall, however, so the small pool for cold water warms up quickly. Tails do noticeably change color. The only moving parts are the heads, which swivel and can be interchanged if bored. Mermaids do not stand up too easily.
Used it in the sink.
Reusable and durable and able to add more later.
It is wet but use it in the sink and it is ok.