http://www.bookofjoe.com/2005/08/rubbermaid_300_.html has a linky: http://www.stockyardsupply.com/page11/index2.html You need a 40 cubic foot container BTW. If the container was 1 foot high, it would be 6.33 x 6.33 feet. or a container 3.42' x 3.42' x 3.42' (roughly) (each side would be 3' 5 1/16"). I do not know what you are planning, although turtles do like to swim, they also like to sun bathe and be on dry land once in a while. If you are planing on having turtles outside, then your 'pond' will have to be at least 48 inches deep with mud as the bottom. due to the winter freeze and that most turtles hibernate in the mud at the bottom of the pond: http://en.allexperts.com/q/Turtles-3543/turtles-winter.htm Of course if the turtles you plan to raise are not native to the area and are subtropical or tropical then they will die in the winter unless you bring them in. Although a 300 gal stock tank may be a good idea for the short term, I think long time you may want to seriously consider something a bit more aesthetically pleasing. Most often ponds are made out of concrete (gunnite really), plastic inserts or the rubberized thick plastic liner - basically one digs the shape they want, smooth out the side and bottom with sand, unroll a flat piece of rubberized plastic, fill and cut to shape. We have one concrete pond and one rubber liner pond - the rubber liner one is easier to keep clean since the rubber is smooth while the concrete is porous.