The Tip of the Iceberg

From our science classes we know that the iceberg that  we can see above the sea level is only 10% its actual size. From this we normally hear people say, "it's only the tip of the iceberg", or "the problems that we face is only the tip of the iceberg", meaning the real problems are much more. 

Using an iceberg ("the tip of the iceberg" to be precise) is one example of using an analogy. 

We can also say "the wealth that you see is only the tip of the iceberg", meaning the actual wealth is much more than that!! 😃