The Rock Hudson of your water garden needs the spotlight.
Choose a special one with lots of character. A mossy coat is nice for shady gardens. Craggy crevices are great for growing some wee plants within.
Display the big guy in a showcase, poolside location. A high visibility spot where it can be most noticed and admired.
Sparkling stage lights (this would be sunshine) should strike it, at least part of the day, for the best show. Place it where water splashes for more glitter.
Whether it’s at pond’s edge or in a waterfall, make it a focal point – especially noticeable in winter when most other performers are gone.
Note – a really big hunk might need reinforcement of the “stage” to keep the liner from sinking. A concrete or flat rock foundation under the liner where show rock sits should do the trick. Pad both sides of the liner where the rock touches.