how deep is the storage area under the floor?

Your question confuses me. There isn’t really any space btw the bottom of the third row seats and the floor. When they’re up, the trunk well goes all the way to the ceiling (about 50” at its max, closer to 47” or 48” at the hatch opening).

Maybe this pic and video will help?

 

I've watched that YR a couple of times, so maybe I'm the one who's confused...

If you fold the seats, they sink nicely into what I'm thinking of as a cargo well. If you wanted to put something into that well, how deep could that item be and not protrude above the level of the floor at the rear of the vehicle?

Thanks!

 

The tape measure photo I took answers that. About a foot