At 23°26´18" south of the equator the tropic of the Capricorn crosses the park. The sun is straight above this latitude at noon december 21th. This marks the beginning of the summer in the southern hemisphere. It is called the Tropic of the Capricorn because the sun is in the constellation Capricorn on this time. This latitude also marks the southern end of the tropics.
You can see a line on the main road and a monument along the road marking the spot.
The Krugertablets are plaques to remember the foundation of the Krugerpark. You can get out of your car (at your own risk) to have a closer look.