The black rubber hose gets wet from a large leak somewhere higher up on the left side of the tub (on the outside of the tub). Water is getting into the tub.
Can't find a diagram for what is up there or any indication what is causing this leak. The common reasons listed for leaks are seemingly not my problem.

While I was checking into this I noticed the door gasket has a hole right where there is an indentation for a screw in the gasket grove in the tub... seems like those indentations create stress (like a hernia?). This is an 18 yo old dishwasher that never gave me any problems before.
I cleaned the gasket and put it in backwards... so now the tear faces the screw and the gasket should again provide a good seal. Time will tell if that works but saved about $75 and it was not leaking from there before.

Update: I'm a disabled 75 yo woman but I managed to pull the dishwasher out and see that water is leaking from a split in t upper curve of the rubber tube going into the tub. Of course a replacement tube is no longer made. LOL
That's capitalism: fails always due to some cheap part that does not last and can't be replaced.