I dont have the car with me today or tape measure handy.. any one know the second row seats are folded, I can fit a tub from home depot in there..

The tub itself is 60x32x20.5 high, im sure the box will make it 65 L x 35 W x 24 H

 

The cargo dimensions vary, depending on where you measure, and what position the seats are in. For example, the roof is curved, so there is more vertical clearance in the middle than the outer edges.

But I just measured my MDX and a 65"x35"x24" box should fit (with a little clearance, but not much).