I always prefer the indigenous people's place names for natural features so from now on, I will use their name for the gorge, Nitmiluk.
Katherine Gorge is part of the Nitmiluk National Park and is actually 13 separate gorges that have been carved out of the ancient sandstone country by the Katherine River. The boat cruise visits the the two lower gorges.
Don't bother to comment. Just enjoy you visit to this ancient landscape.