Try and sample a fish dish called cha ca vlong. It's a Hanoi dish which we found to be amazing. We didn't get to the venue in the link but I'm sure it's fantastic wherever you eat. http://mobile.nytimes.com/2012/05/3...-a-dish-inspired-by-a-dive-in-hanoi.html?_r=0
Have just booked a car for the day.
Went to tripadvisor and selected one with high marks and a lot of reviews. USD 80.00 for the day.
We'll decide what to do re lunch, boats etc when we get there. And we can decide ourselves when to return to Hanoi.
I'll post the company details if I think it was good.