I am looking for a large plastic underbed type box with no lid and I want it for a pool for my two ducks. They currently have one in their pen but I would like a larger one for the garden. 6" / 8" deep would be fine. Any suggestions please.

A gift wrap storage box would be the right size. They all come with a lid so you would just take that off. Most home improvement stores sell them in different sizes.

See here

Thanks, the one we have is about 28" long and I saw one in Wilkinsons today about 30" long. I'm just waiting around now to see if anyone such as yourself comes up with a really good idea/deal.

You could also look at purchasing a small plastic kiddie pool. I think this would be a better option.

See here

Will you be putting it "on" the ground, or digging a bit to set it flush, or nearly flush "in" the ground?
I've seen some sports equipment storage boxes that are about a foot deep and 6' long and are solidly enough constructed to sit above ground... if it's going to be set in-ground, the kiddie pool might be your best and most cost effective option.

Have you Got a Poundstretcher store near you ?
They have a big range of these boxes www.instoreretail.co.uk
They are also use the Instore Brand name(Converting over slowly)

There is a store locater on the link above

The kiddie pool looks ideal and given me food for thought. I didn't know Poundstreatcher were changing names, but I did see a good selection a week or so ago, so when we are next able, I'll look in there. As for how it will be positioned. A few years ago, we bought a patio pool which is a rubber/plastic pool with a wooden frame. This stands about 12" high and I've had to create a walkway for them. After baiting the gang-plank with lettuce, they soon discovered this new deep water. I would rather have a shallower pool and sink it a few inches.

There is one draw-back. Ducks mate in water, and since it has been in situ, they've been "at it" all the time. (lol)