How to make a cube that is a different colour when you step inside?

I want to make a cube that will sit underneath my water, so what when I walk ‘into’ the water (and am underneath it, everything is a slightly different colour. Is this possible? And if so, how? Thanks!

I think this question has already been answered

You can give the cube a box collider, and check isTrigger. Then give it a script that makes it turn a different color using OnTriggerEnter or OnTriggerStay.