it is a big solid plastic mold about 5'longx3'widex2 1/2'deep i have a realy old pond filter but the problem with building the pond wider is there are huge palms pygmy and queen palms around the pond almost to the edge i was thinking of making it 4-5' deeper by either taking out the mold digging it deeper at the bottom and a little bit wider by digging around the trees wich i still want there and using a thick heavey duty pond liner and puting a layer of sand at least 4" and driftwood and small river rocks as well as the bigger filter and have some lilies at the top.