'Standing water'

Sometimes you just know when you have your blip for the day, no matter what might crop up later on.

Was driving through to Edinburgh this morning when the traffic came to a standstill. For 25 minutes. And there was a low loader with a digger on it in front of me, so I couldn't see past it.
Eventually a police car and a Highways Agency vehicle went past on the hard shoulder, displaying a 'Flood' sign on it's roof. And the traffic report then came on the radio saying that there was standing water on the M9. 
A short while later this is what I eventually went through.
Standing water? - It had WAVES!! The water was so deep driving through it I really thought I might not make it.
Apparently the road was subsequently closed for around 4 hours - think I may have been one of the last through it.
The joys of winter commuting in Scotland!