I had the privilege of rocking up in NOLA in a sodding huge cruise ship some years ago after whizzing across the Atlantic. I am well aware that it wasn't the "greenest" action I have ever performed.

It takes nearly a day to crawl up the river M from the Gulf of Mexico. A 18 deck monster at around 180,000 tonnes has to take it easy to avoid damaging the levees with its wash, scouring out the river bed etc. At one point, over the course of 45 minutes, our captain decided to overtake a tanker (showboating). A few minutes later we had to park up in a herringbone formation to wait our turn to dock, which took several hours.

I think it is around 70-80 miles from the sea to NOLA. From 18 storeys up a river as huge as the Mississippi still looks huge. The levees don't look very large though from up there though, they look very flat and fragile.

I studied Civil Engineering in Plymouth (Devon, not MA) and that trip on a cruise ship gave me quite a perspective on engineering works and nature.

@pjot - if you get a chance, take a run up the Mississippi on a really big ship. Its quite an eye opener.