Interesting terrain in FS9 default scenery.

[timcclayton]

There are 6 well-known ones that are fixed by a freeware download:

To see the 15,000 ft hole error at Millwood Lake, start at Glenn Winchester airport (2AR6) and fly heading 175 for 6.5 nm.
To see the 11,500 ft hole error at Stockton Lake, start at Stockton Mun (MO3) and fly heading 120 for 6 nm.
To see the big hill near Memphis error, start at Delta Flying Service Inc airport (MS65) and fly heading 117 for 2 nm.
To see the floating runways at Davis airport (KMKO), simply start at Davis airport (KMKO)!
To see the Girdwood river 'cliffs', simply start at Girdwood airport (AQY)!
To see the 100,000+/60,000 ft chasm/spire, start at Kamarang (SYKM) and fly heading 163 for 6 nm.

(taken from the readme.txt file of the fix by Joshua Robertson)