Here are two water mini games. These are plastic games that you fill up with water via a hole in the top. You can then push a button on the front to create currents in the water that move plastic rings around. The objective is to catch the rings on little hooks or spikes inside the game. (see what they did before video games were quite so popular?) On the more complex one, Sonic may spin! These are from 1994, in any toy shop, and are around 4.99 pound (likely for the larger one).

Here's a clearer look at the red water game. A diamond shaped panel inside has stock jumping Sonic on it, and you can see how the rings have dried onto the inside of the game as it has no stopper in the top. 

In the gallary is the real deal! And, you can even see it with its original box...how rare! This is called "Sonic Water Wizard". It features a probably spinning Sonic & many colored rings (seen in the loop) Pushing the button causes a current in the water-filled game so you can move the rings around. The box has a sort of interesting/altered stock art of Sonic, sitting on a jet of water. You can also notice a Buzz Bomber near the top of the loop.